Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Haruyuki Nakano Last modified date:2020.06.19

Professor / interdisciplinary chemistry / Department of Chemistry / Faculty of Sciences


Papers
1. C. Yang, Y. Watanabe, N. Yoshida, H. Nakano, Applicability of density functional and wave function theories combined with the three-dimensional reference interaction site model self-consistent field method to the d-d transitions of a transition metal aqua complex, 2nd International Conference on Materials Research and Innovation, ICMARI 2019 IOP Conference Series: Materials Science and Engineering, 10.1088/1757-899X/773/1/012061, 773, 1, 2020.03, The applicability of density functional theory (DFT) and wave function theory combined with the three-dimensional reference interaction site model self-consistent field method to the d-d transitions of transition metal aqua complexes was examined using [Cr(H2O)6]3+ in aqueous solution as an example. DFTs with hybrid functionals, multiconfigurational self-consistent field followed by perturbation theory, and coupled-cluster singles and doubles (CCSD) followed by the equation of motion CCSD, gave reasonable d-d transition energies..
2. Keisuke Sudoh, Yuna Satoh, Ko Furukawa, Haruyuki Nakano, Yoshihiro Matano, Synthesis and optical, magnetic, and electrochemical properties of 5,10,15,20-tetraaryl-5,15-diazaporphyrin - Tertiary amine conjugates, Journal of Porphyrins and Phthalocyanines, 10.1142/S1088424619500822, 24, 1-3, 286-297, 2020.01, We report on the synthesis and optical, magnetic, and electrochemical properties of nickel(II) and copper(II) complexes of 5,10,15,20-tetraaryl-5,15-diazaporphyrin-tertiary amine (TADAP-TA) conjugates. Metal-templated cyclization reactions of 9-(4-(dimethylamino)phenyl)amino-1-chloro-5-mesityldipyrrin and 9-(4-(diphenylamino)phenyl)amino-1-chloro-5-mesityldipyrrin (mesityl = 2,4,6-trimethylphenyl) with nickel(II) or copper(II) acetate afforded the corresponding metal(II) complexes of TADAP-TA. The 20π, 19π, and 18π oxidation states of the DAP ring in the TADAP - TAs were reversibly interconvertible by redox reactions. NMR spectroscopy of the 20π and 18π Ni-TADAP - TAs revealed their antiaromatic and aromatic characters, respectively, whereas electron paramagnetic resonance spectroscopy of the 19π Ni-TADAP-TAs showed effective delocalization of an unshared electron spin in the DAP ring. The interconversion between the three oxidation states of TADAP - TAs also caused a distinct change in the optical properties of the DAP π-electron system. Notably, all the 18π dications exhibited weak and broad absorption bands in the near infrared region owing to the charge-transfer from the peripheral tertiary amine units (donor) to the cationic DAP center (acceptor). Cyclic voltammetry of TADAP - TAs exhibited the reversible 20π/19π and 19π/18π redox couples and the irreversible amine oxidation at the periphery. The electrochemical oxidation of the Ni-TADAP-triphenylamine conjugate generated reactive ammoniumyl radicals, which underwent intermolecular coupling to form a polymer of TADAP-TA on the electrode surface..
3. Shoichi Tanimoto, Norio Yoshida, Tsuyoshi Yamaguchi, Seiichiro L. Ten-No, Haruyuki Nakano, Effect of Molecular Orientational Correlations on Solvation Free Energy Computed by Reference Interaction Site Model Theory, Journal of Chemical Information and Modeling, 10.1021/acs.jcim.9b00330, 59, 9, 3770-3781, 2019.09, The effect of molecular orientational correlations on the solvation free energy (SFE) of one-dimensional and three-dimensional reference interaction site models (1D- and 3D-RISM) is investigated. The repulsive bridge correction (RBC) and the partial wave (PW) expansion are representative approaches for accounting for the orientational correlation partially lacking in original 1D- and 3D-RISM. The SFEs of 1D- and 3D-RISM for a set of small organic molecules are compared with the simulation results. Accordingly, the SFE expressions, based on RBC and PW, provide more accurate results than those of the uncorrected HNC or KH SFE expressions, which indicates that accounting for molecular orientational dependencies significantly contributes to the improvement of the SFE. The SFE component analysis indicates that the nonpolar component mainly contributes to the correction. The dependence of the error in the RISM SFE on the number of solute sites is examined. In addition, we discuss the differences between 1D- and 3D-RISM through the effect of these corrections..
4. Daisuke Okamoto, Yoshihiro Watanabe, Norio Yoshida, Haruyuki Nakano, Implementation of state-averaged MCSCF method to RISM- and 3D-RISM-SCF schemes, Chemical Physics Letters, 10.1016/j.cplett.2019.05.051, 730, 179-185, 2019.09, The state-averaged multiconfiguration self-consistent field (MCSCF) method was implemented to the reference interaction site model and three-dimensional reference interaction site model (RISM and 3D-RISM) SCF schemes, where the electronic structures of multiple states and solvation structure are determined simultaneously by the state-averaged MCSCF method and state-specific RISM-SCF/3D-RISM-SCF scheme, respectively, in a single calculation. The method was applied to the potential energy curves of the low-lying states of NaCl in aqueous solution and solvation shifts of the excitation energy of formaldehyde and p-nitroaniline. The results showed good agreement with those of the state-specific MCSCF and/or experiments..
5. Chen Yang, Yoshihiro Watanabe, Norio Yoshida, Haruyuki Nakano, Three-Dimensional Reference Interaction Site Model Self-Consistent Field Study on the Coordination Structure and Excitation Spectra of Cu(II)-Water Complexes in Aqueous Solution, Journal of Physical Chemistry A, 10.1021/acs.jpca.9b01364, 123, 15, 3344-3354, 2019.04, The molecular and solvation structures of the hydrated Cu 2+ ions and their excitation spectra were investigated using the Kohn-Sham density functional theory (DFT) and the three-dimensional reference interaction site model (3D-RISM) self-consistent field method. Five stable geometrical structures were found to exist in aqueous solution: the distorted octahedral [Cu(H 2 O) 6 ] 2+ in C i and D 2h symmetries, the square pyramidal and trigonal bipyramidal [Cu(H 2 O) 5 ] 2+ , and the square planar [Cu(H 2 O) 4 ] 2+ . The distorted octahedral structure in the C i symmetry is preferred in [Cu(H 2 O) 6 ] 2+ , and the square pyramidal and trigonal bipyramidal [Cu(H 2 O) 5 ] 2+ show almost the same stability. Among these geometries, the six-coordinate complex [Cu(H 2 O) 6 ] 2+ in the C i symmetry had the lowest Helmholtz energy. [Cu(H 2 O) 6 ] 2+ had a distorted octahedral structure, that is, two long axial bonds and four short equatorial bonds. The spatial and radial distribution function analyses for [Cu(H 2 O) 5 ] 2+ and [Cu(H 2 O) 4 ] 2+ showed that [Cu(H 2 O) 5 ] 2+ and [Cu(H 2 O) 4 ] 2+ had one and two solvent water molecules that constituted a distorted octahedron with ligand water distribution. The coordination numbers (CNs) derived from the distribution functions were 5.2-5.4 for [Cu(H 2 O) 5 ] 2+ and 5.3 for [Cu(H 2 O) 4 ] 2+ . These results indicated that the Cu 2+ ion in an aqueous solution had 5-6 coordination water molecules in the first hydration shell and some structures with different CNs may interchange in the solution. The excitation energies and electronic configurations of low-lying d-d excited states were calculated using the time-dependent DFT with the electric field generated by 3D-RISM. The orbital energies and electronic configurations were in a similar picture to those of the classical crystal field theory because of the highly symmetrical features of all structures. In [Cu(H 2 O) 6 ] 2+ , the degeneracies of orbitals were resolved, whereas in [Cu(H 2 O) 5 ] 2+ and [Cu(H 2 O) 4 ] 2+ , weak and strong quasi-degeneracies remained. As a result, only the four-coordinate complex generated third and fourth excited states, whereas in other complexes, there were no obvious characters of degeneracies. The resulting excitation energies were in good agreement with the absorption spectra..
6. Mai Mutoh, Keisuke Sudoh, Ko Furukawa, Mao Minoura, Haruyuki Nakano, Yoshihiro Matano, Synthesis of Redox-switchable 5,15-Dialkyl-10,20-diaryl-5,15-diazaporphyrins and Diversification of their N-Alkyl Groups, Asian Journal of Organic Chemistry, 10.1002/ajoc.201900085, 8, 3, 352-355, 2019.03, Nickel(II) and copper(II) complexes of redox-switchable 20π, 19π, and 18π 5,15-dialkyl-10,20-diaryl-5,15-diazaporphyrins were prepared through a metal-templated cyclization method. Furthermore, the terminal silyloxy groups in the peripheral N-alkyl chains were transformed into hydroxy groups by deprotection. It is worth noting that redox reactions between the 19π and 18π systems bearing hydroxy groups caused a change in the water solubility of the diazaporphyrin chromophore..
7. Nirun Ruankaew, Norio Yoshida, Yoshihiro Watanabe, Akira Nakayama, Haruyuki Nakano, Saree Phongphanphanee, Distinct ionic adsorption sites in defective Prussian blue
A 3D-RISM study, Physical Chemistry Chemical Physics, 10.1039/c9cp04355a, 21, 40, 22569-22576, 2019.01, Ferric hexacyanoferrate (FeHCF) or Prussian blue (PB) exhibits selective alkali ion adsorption and has great potential for use in various applications. In the present work, alkali ion (Li+, Na+, K+, and Cs+) and water configurations in defective PB (d-PB) were studied by using the statistical mechanics of molecular liquids. The three-dimensional (3D) distribution functions of the ions and water were determined by solving the 3D-reference interaction site model (RISM) equation of systems of a unit lattice of d-PB in electrolyte solutions, i.e., LiCl, NaCl, KCl, and CsCl. The results show the difference in the ion-water configurations and distributions between small (Li+ and Na+) and large ions (K+ and Cs+). The adsorption sites of Li+ and Na+ are located off-center and lie on the diagonal axis. By contrast, the larger ions, K+ and Cs+, are adsorbed at the center of the unit cell. The degree of dehydration due to the adsorption of alkali ions indicates that there was no water exchange during Li+ and Na+ adsorption, whereas two and three water molecules were removed after adsorption of K+ or Cs+ in the unit cell..
8. Keisuke Sudoh, Ko Furukawa, Haruyuki Nakano, Soji Shimizu, Yoshihiro Matano, Synthesis and properties of redox-switchable zinc complexes of 10,15,20-triaryl-15-aza-5-oxaporphyrin, Heteroatom Chemistry, 10.1002/hc.21456, 29, 5-6, 2018.12, The synthesis, aromaticity, and optical and electrochemical properties of zinc(II) complexes of 10,15,20-triaryl-15-aza-5-oxaporphyrin (TriAAOP) were investigated. Metal-templated cyclization of a zinc(II) 1,19-dichloro-5,10,15-triaryl-10-azatetrapyrrin complex with an oxygen source afforded 20π TriAAOP in the neutral form. Oxidation of 20π TriAAOP with silver (I) hexafluorophosphate generated the 19π radical cation or 18π dication depending on the content of oxidant used. The interconversion between the three oxidation states (18π, 19π, and 20π) resulted in distinct changes in the aromaticity and optical properties of the 15-aza-5-oxaporphyrin π-system. Nuclear magnetic resonance spectroscopy of 20π TriAAOP revealed its antiaromatic character, whereas that of the 18π TriAAOP dication showed its aromatic character. The combined effect of the two meso-heteroatoms was directly reflected in the redox properties of the porphyrin ring; TriAAOP was reduced more easily and more difficult to oxidize than the zinc(II) complex of 5,10,15,20-tetraaryl-5,15-diaz-aporphyrin (TADAP). In the ultraviolet-visible-near–infrared spectra of the materials, the lowest-energy electronic excitations of the 19π and 18π TriAAOP derivatives were considerably red-shifted compared with those of the isoelectronic TADAP derivatives. Based on the results of density functional theory calculations, it was concluded that the observed differences between TriAAOP and TADAP would arise from the high electronegativity of oxygen; specific frontier orbitals of the TriAAOP π-systems were energetically stabilized relative to those of the TADAP π-system. The present findings corroborate that the meso-modification of a porphyrin rings with different kinds of heteroatoms is a promising strategy to fine tune their light-response properties that are switchable by reversible single electron transfer processes..
9. Satoshi Omomo, Takuma Sugai, Mao Minoura, Haruyuki Nakano, Yoshihiro Matano, Direct and Regioselective Amination of β-Unsubstituted 5,15-Diazaporphyrins with Amines
A Convenient Route to Near-Infrared-Responsive Diazaporphyrin Sensitizers, Angewandte Chemie - International Edition, 10.1002/anie.201800471, 57, 14, 3797-3800, 2018.03, We have established a convenient method for the base-promoted direct amination of β-unsubstituted 5,15-diazaporphyrins (DAPs) with secondary and primary amines to produce 3,7,13,17-tetraamino- and 3-amino-DAPs, respectively, regioselectively. The amino groups attached at the periphery cause significant red shifts of the absorption bands as a result of their perturbation of the HOMO and/or LUMO in the DAP π-system. The palladium complex of a 3,7,13,17-tetrakis(diphenylamino)-DAP generated singlet oxygen in high yield under irradiation with near-infrared light..
10. Keisuke Sudoh, Takuroh Hatakeyama, Ko Furukawa, Haruyuki Nakano, Yoshihiro Matano, Redox switchable 19π and 18π 5,10,20-triaryl-5,15-diazaporphyrinoid–nickel(II) complexes, Journal of Porphyrins and Phthalocyanines, 10.1142/S1088424618500529, 1-10, 2018.01, The synthesis and optical, electrochemical, and magnetic properties of nickel(II) complexes of 5,10,20-triaryl-5,15-diazaporphyrin (TriADAP) are reported. Metal-templated cyclization of unsymmetrically substituted nickel(II)–bis(1-amino-9-chloro-5-mesityldipyrrin; mesityl = 2,4,6-trimethylphenyl) complexes afforded the corresponding TriADAPs or 5-aryl-15-benzyl-10,20-dimesityl-5,15-diazaporphyrin, depending on the combination of base and solvent. The latter macrocycle was converted to TriADAP by deprotection of the (Formula presented.)-benzyl group through Pd/C-promoted hydrogenation. TriADAPs were isolated in both 18(Formula presented.) (cation) and 19(Formula presented.) (neutral) forms. The interconversion between these two oxidation states resulted in a distinct change in the optical properties of the DAP (Formula presented.)-system. NMR spectroscopy of the 18(Formula presented.) TriADAP cations showed that they had aromatic character, whereas EPR spectroscopy of the 19(Formula presented.) TriADAP showed a highly delocalized electron spin of the (Formula presented.)-radical. The para substituents of the (Formula presented.)-aryl groups of TriADAPs had a small but distinct impact on their HOMO and LUMO energies. The change in the net charge of one electron was directly reflected in the redox properties of the DAP ring; TriADAP was more easily reduced and less easily oxidized than DAP. The difference in the net charge was also reflected by the shielding of the pyrrolic β-protons observed in the (Formula presented.)H NMR spectra. The present results confirm that TriADAP is a highly promising framework for constructing a new class of azaporphyrin-based materials with 18(Formula presented.)–19(Formula presented.) redox-switchable optical and magnetic properties..
11. Ryo Fujiki, Yukako Kasai, Yuki Seno, Toru Matsui, Yasuteru Shigeta, Norio Yoshida, Haruyuki Nakano, A computational scheme of p
K a values based on the three-dimensional reference interaction site model self-consistent field theory coupled with the linear fitting correction scheme, Physical Chemistry Chemical Physics, 10.1039/c8cp04354j, 20, 43, 27272-27279, 2018.01, A scheme for quantitatively computing the acid dissociation constant, pKa, of hydrated molecules is proposed. It is based on the three-dimensional reference interaction site model self-consistent field (3D-RISM-SCF) theory coupled with the linear fitting correction (LFC) scheme. In LFC/3D-RISM-SCF, pKa values of target molecules are evaluated using the Gibbs energy difference between the protonated and unprotonated states calculated by 3D-RISM-SCF and the parameters fitted by the LFC scheme to the experimental values of training set systems. The pKa values computed by LFC/3D-RISM-SCF show quantitative agreement with the experimental data..
12. Takuma Sugai, Mao Minoura, Haruyuki Nakano, Yoshihiro Matano, β-functionalization of 5, 15-diazaporphyrins with phosphorus, oxygen, and sulfur-containing substituents, Bulletin of the Chemical Society of Japan, 10.1246/bcsj.20180123, 91, 8, 1264-1266, 2018.01, The β-functionalization of 5, 15-diazaporphyrins (DAPs) with phosphoryl, phenoxy, sulfanyl, and sulfonyl groups was achieved by either cross-coupling or aromatic nucleophilic substitution reactions of β-bromo- and β, β′-dibromo-DAPs. The heteroatom-containing functional groups at the β- positions strongly affected the redox properties of the DAP π-systems..
13. Keisuke Sudoh, Takaharu Satoh, Toru Amaya, Ko Furukawa, Mao Minoura, Haruyuki Nakano, Yoshihiro Matano, Syntheses, Properties, and Catalytic Activities of Metal(II) Complexes and Free Bases of Redox-Switchable 20π, 19π, and 18π 5,10,15,20-Tetraaryl-5,15-diazaporphyrinoids, Chemistry - A European Journal, 10.1002/chem.201703664, 23, 64, 16364-16373, 2017.11, In spite of significant advances in redox-active porphyrin-based materials and catalysts, little attention has been paid to 20π and 19π porphyrins because of their instability in air. Here we report the meso-modification of 5,10,15,20-tetraarylporphyrin with two nitrogen atoms, which led to redox-switchable 20π, 19π, and 18π 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (TADAPs). Three kinds of metal(II) complexes and free bases of TADAP were prepared by the metal-templated annulation of the corresponding metal-bis(dipyrrin) complexes. The inductive and resonance effects of the meso-nitrogen atoms on the aromatic, optical, electrochemical, and magnetic properties of the entire TADAP π-systems were assessed by using various spectroscopic measurements and density functional theory calculations. The aromaticity and π–π* electronic transition energies of the TADAPs varied considerably, and were shown to be dependent on the oxidation states of the π-systems. In contrast to the isoelectronic 5,10,15,20-tetraarylporphyrin derivatives, the 20π and 19π TADAPs were chemically stable under air. In particular, the 19π TADAP radical cations were extremely stable towards dioxygen, moisture, and silica gel. This reflected the low-lying singly occupied molecular orbitals of their π-systems and the efficient delocalization of their unshared electron spin. The capability of MgTADAP to catalyze aerobic biaryl formation from aryl Grignard reagents was demonstrated, which presumably involved a 19π/20π redox cycle..
14. Yuichi Tanaka, Yukio Kawashima, Norio Yoshida, Haruyuki Nakano, Solvatochromism and preferential solvation of Brooker's merocyanine in water–methanol mixtures, Journal of Computational Chemistry, 10.1002/jcc.24902, 38, 28, 2411-2419, 2017.10, The excitation energy of Brooker's merocyanine in water–methanol mixtures shows nonlinear behavior with respect to the mole fraction of methanol, and it was suggested that this behavior is related to preferential solvation by methanol. We investigated the origin of this behavior and its relation to preferential solvation using the three-dimensional reference interaction site model self-consistent field method and time-dependent density functional theory. The calculated excitation energies were in good agreement with the experimental behavior. Analysis of the coordination numbers revealed preferential solvation by methanol. The free energy component analysis implied that solvent reorganization and solvation entropy drive the preferential solvation by methanol, while the direct solute–solvent interaction promotes solvation by water. The difference in the preferential solvation effect on the ground and excited states causes the nonlinear excitation energy shift..
15. Satoshi Omomo, Yukihiro Tsuji, Kenichi Sugiura, Tomohiro Higashino, Haruyuki Nakano, Hiroshi Imahori, Yoshihiro Matano, Unsymmetrically Substituted Donor–π–Acceptor-Type 5,15-Diazaporphyrin Sensitizers
Synthesis, Optical and Photovoltaic Properties, ChemPlusChem, 10.1002/cplu.201700051, 82, 5, 695-704, 2017.05, The first examples of unsymmetrical β-substituted donor–π–acceptor (D–π–A)-type 5,15-diazaporphyrin (DAP) sensitizers with both p-aminophenyl and p-carboxyphenyl groups at their peripheral 3-, 7-, 13-, and/or 17-positions have been synthesized for use in dye-sensitized solar cells (DSSCs). UV/Vis absorption and emission spectroscopy, electrochemical measurements, and DFT calculations revealed that these D–π–A dyes exhibit high light-harvesting properties over the whole visible range because of the intrinsic charge-transfer character of their electronic transitions. The cell performances of TiO2-based DSSCs fabricated with the newly prepared DAP derivatives were evaluated under standard AM1.5 conditions. Among the four dyes examined, 13,17-bis(p-carboxyphenyl)-3,7-bis[p-(N,N-dimethylamino)phenyl]-DAP showed the highest power conversion efficiency (2.0 %), which was 20 times larger than that obtained with 3-(p-carboxyphenyl)-DAP. These results show that the DAP chromophore could be used as the electron-accepting π unit in various types of functional dyes..
16. Masahiro Kawamata, Takuma Sugai, Mao Minoura, Yasuhisa Maruyama, Ko Furukawa, Cole Holstrom, Victor N. Nemykin, Haruyuki Nakano, Yoshihiro Matano, Nitrogen-Bridged Metallodiazaporphyrin Dimers
Synergistic Effects of Nitrogen Bridges and meso-Nitrogen Atoms on Structure and Properties, Chemistry - An Asian Journal, 10.1002/asia.201700204, 12, 7, 816-821, 2017.04, NH-bridged and pyrazine-fused metallodiazaporphyrin dimers have been prepared from nickel(II) and copper(II) complexes of 3-amino-5,15-diazaporphyrin by Pd-catalyzed C−N cross-coupling and oxidative dimerization reactions, respectively. The synergistic effects of the nitrogen bridges and meso-nitrogen atoms play major roles in enhancing the light-harvesting properties and delocalization of an electron spin over the entire π-skeletons of the metallodiazaporphyrin dimers..
17. Nirun Ruankaew, Norio Yoshida, Yoshihiro Watanabe, Haruyuki Nakano, Saree Phongphanphanee, Size-dependent adsorption sites in a Prussian blue nanoparticle
A 3D-RISM study, Chemical Physics Letters, 10.1016/j.cplett.2017.06.053, 684, 117-125, 2017, The specific adsorption of alkali ions, Li+, Na+, K+, and Cs+, in electrolyte solutions on Prussian blue (PB) is investigated by using the three-dimensional (3D) reference interaction site-model (RISM) theory. The results from 3D-RISM show dramatically different adsorption sites between large ions (K+ and Cs+) and small ions (Li+ and Na+). The small ions are adsorbed at the channel entrance sites without the water–ion exchange mechanism. In contrast, the large ions are adsorbed in PB by the water–ion exchange mechanism, and the adsorption site of large ions is located at the center of the cage or at the interstitial site..
18. Shoichi Tanimoto, Masahiro Higashi, Norio Yoshida, Haruyuki Nakano, The ion dependence of carbohydrate binding of CBM36
An MD and 3D-RISM study, Journal of Physics Condensed Matter, 10.1088/0953-8984/28/34/344005, 28, 34, 2016.07, The molecular recognition process of the carbohydrate-binding module family 36 (CBM36) was examined theoretically. The mechanism of xylan binding by CBM36 and the role of Ca2+ were investigated by the combined use of molecular dynamics simulations and the 3D reference interaction site model method. The CBM36 showed affinity for xylan after Ca2+ binding, but not after Mg2+ binding. Free-energy component analysis of the xylan-binding process revealed that the major factor for xylan-binding affinity is the electrostatic interaction between the Ca2+ and the hydroxyl oxygens of xylan. The van der Waals interaction between the hydrophobic side chain of CBM36 and the glucopyranose ring of xylan also contributes to the stabilization of the xylan-binding state. Dehydration on the formation of the complex has the opposite effect on these interactions. The affinity of CBM36 for xylan results from a balance of the interactions between the binding ion and solvents, hydrophilic residues around xylan, and the hydroxyl oxygens of xylan. When CBM binds Ca2+, these interactions are well balanced; in contrast, when CBM binds Mg2+, the dehydration penalty is excessively large..
19. Yuki Seno, Norio Yoshida, Haruyuki Nakano, Theoretical analysis of complex formation of p-carboxybenzeneboronic acid with a monosaccharide, Journal of Molecular Liquids, 10.1016/j.molliq.2015.12.063, 217, 93-98, 2016.05, Changes in the acid dissociation constant, pKa, of p-carboxybenzeneboronic acid (PCBA) upon complex formation with monosaccharide are considered by using the three-dimensional reference interaction site model self-consistent field theory. The pKa of PCBA is lowered through complex formation, which is consistent with experimental observations. Free energy component analysis of the dissociation reaction was performed to investigate the details of the contribution to the pKa shift. The magnitudes of the changes in both the electronic energy and the solvation free energy were smaller for the PCBA-complex than for PCBA. These smaller changes can be attributed to the delocalization of the excess charge and to a reduction of the solvent-accessible area near the boric acid group because of the steric bulk of the monosaccharide..
20. Takaharu Satoh, Mao Minoura, Haruyuki Nakano, Ko Furukawa, Yoshihiro Matano, Redox-switchable 20π-, 19π-, and 18π-electron 5,10,15,20-tetraaryl-5,15-diazaporphyrinoid nickel(II) complexes, Angewandte Chemie - International Edition, 10.1002/anie.201510734, 55, 6, 2235-2238, 2016.02, The first examples of air-stable 20π-electron 5,10,15,20-tetraaryl-5,15-diaza-5,15-dihydroporphyrins, their 18π-electron dications, and the 19π-electron radical cation were prepared through metal-templated annulation of nickel(II) bis(5-arylamino-3-chloro-8-mesityldipyrrin) complexes followed by oxidation. The neutral 20π-electron derivatives are antiaromatic and the cationic 18π-electron derivatives are aromatic in terms of the magnetic criterion of aromaticity. The meso N atoms in these diazaporphyrinoids give rise to characteristic redox and optical properties for the compounds that are not typical of isoelectronic 5,10,15,20-tetraarylporphyrins. N makes all the difference: Redox-switchable 20π-, 19π-, and 18π-electron 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids are prepared through metal-templated annulation of NiII bis(dipyrrin) complexes followed by oxidation. The meso N atoms in these diazaporphyrinoids give rise to characteristic redox and optical properties for the compounds that are not typical of isoelectronic 5,10,15,20-tetraarylporphyrins..
21. Yuichi Tanaka, Norio Yoshida, Haruyuki Nakano, Three-dimensional reference interaction site model self-consistent field analysis of solvent and substituent effects on the absorption spectra of Brooker's merocyanine, Journal of Computational Chemistry, 10.1002/jcc.23980, 36, 22, 1655-1663, 2015.08, Solvent and substituent effects on the absorption spectra of Brooker's merocyanine (BM) are investigated using the three-dimensional reference interaction site model self-consistent field method and time-dependent density functional theory. The π-π∗ excitation energies are computed for BM and its derivative 2,6-di-tert-butyl (di-t-Bu) BM. The behaviors of the computed excitation energies with increasing solvent polarity are in good agreement with those of the corresponding experimental measurements. In addition, analysis of the solute-solvent interaction energies and spatial distribution functions reveals that the effects of the solvent on the absorption spectra are reduced by the steric hindrance of the t-Bu groups. Furthermore, from the difference in the solute-solvent interaction energies of BM and di-t-Bu BM, it is shown that the effect of the t-Bu substituents on the absorption spectrum is greater in high-polarity solvents..
22. Satoshi Omomo, Ko Furukawa, Haruyuki Nakano, Yoshihiro Matano, Comparison of electronic effects of β-Aryl substituents on optical and electrochemical properties of 5,15-diazaporphyrin φ-systems, Journal of Porphyrins and Phthalocyanines, 10.1142/S1088424615500509, 19, 6, 775-785, 2015.06, The syntheses and optical/electrochemical properties of 3-Aryl-10,20-dimesityl-5,15-diazaporphyrin-metal complexes (MDAPs; mesityl = 2,4,6-trimethylphenyl; M = Ni, Zn) are reported. Treatment of 3-bromo-MDAPs with arylboronic acids in the presence of a Pd catalyst and a bulky phosphine ligand in a dioxane-water mixed solvent afforded the corresponding 3-Aryl-MDAPs in moderate to good yields. X-ray crystallographic analysis of p-EtO2CC6H4-NiDAP showed that the β-Aryl group was tilted toward the NiDAP ring, with a dihedral angle of 21.7°. In the UV-visible absorption spectra, all the Ar-MDAPs showed intense Q-bands attributable to HOMO-to-LUMO transitions. The para substituents were found to influence the HOMO energies, which eventually resulted in fine tuning of the HOMO-LUMO gaps of the diazaporphyrin chromophores. It is worth noting that the p-Ph 2NC6H4-ZnDAP showed broad absorption and emission bands in the visible-near-infrared regions. The large Stokes shifts and their linear solvation energy relationships vs. orientation polarizability show that this Ph 2N-substituted derivative has intrinsically high charge transfer from the triphenylamine (donor) to the ZnDAP (acceptor) unit. These experimental observations were supported by theoretical calculations for model Ar-ZnDAP compounds. These results confirm that the introduction of a highly electron-donating aryl group at the peripheral β-carbon is a promising strategy for enhancing the light-harvesting and light-emitting abilities of diazaporphyrin-based φ-systems in the visible-near-infrared regions..
23. Fawzi Abou-Chahine, Daisuke Fujii, Hiroshi Imahori, Haruyuki Nakano, Nikolai V. Tkachenko, Yoshihiro Matano, Helge Lemmetyinen, Synthesis and Photophysical Properties of Two Diazaporphyrin-Porphyrin Hetero Dimers in Polar and Nonpolar Solutions, Journal of Physical Chemistry B Materials, 10.1021/jp510903a, 119, 24, 7328-7337, 2015.06, Two diazaporphyrin (DAP)-porphyrin hetero dimers, in β-meso and β-β configurations, were prepared to study their photoinduced intramolecular electron transfer properties. The two meso nitrogen atoms in the porphyrin ring of DAP change its redox potential, making DAP more easily reduced, compared to its porphyrin counterpart. A charge-transfer from porphyrin to DAP in both hetero dimers was verified by versatile optical spectroscopic methods. The steady-state fluorescence spectra indicated an efficient intramolecular exciplex formation for both dimers. For the β-meso dimer, ultrafast time-resolved spectroscopic methods revealed the subpicosecond formation of two types of primary short-living (1-18 ps) intramolecular exciplexes, which relaxed in toluene to form a long-living final exciplex (1.4 ns) followed by a longer-living charge transfer complex (>5 ns). However, in benzonitrile, the lifetime of the final exciplex was longer (660 ps) as was that of the charge transfer complex (180 ps). The β-β analogue formed similar short-living exciplexes in both solvents, but the final exciplex and the charge transfer state had significantly shorter lifetimes. The electrochemical redox potential measurements and density functional theory calculations supported the proposed mechanism..
24. Yukako Kasai, Norio Yoshida, Haruyuki Nakano, Theoretical analysis of co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture, Journal of Chemical Physics, 10.1063/1.4921432, 142, 20, 2015.05, The co-solvent effect on the proton transfer reaction of glycine in a water-acetonitrile mixture was examined using the reference interaction-site model self-consistent field theory. The free energy profiles of the proton transfer reaction of glycine between the carboxyl oxygen and amino nitrogen were computed in a water-acetonitrile mixture solvent at various molar fractions. Two types of reactions, the intramolecular proton transfer and water-mediated proton transfer, were considered. In both types of the reactions, a similar tendency was observed. In the pure water solvent, the zwitterionic form, where the carboxyl oxygen is deprotonated while the amino nitrogen is protonated, is more stable than the neutral form. The reaction free energy is -10.6 kcal mol-1. On the other hand, in the pure acetonitrile solvent, glycine takes only the neutral form. The reaction free energy from the neutral to zwitterionic form gradually increases with increasing acetonitrile concentration, and in an equally mixed solvent, the zwitterionic and neutral forms are almost isoenergetic, with a difference of only 0.3 kcal mol-1. The free energy component analysis based on the thermodynamic cycle of the reaction also revealed that the free energy change of the neutral form is insensitive to the change of solvent environment but the zwitterionic form shows drastic changes. In particular, the excess chemical potential, one of the components of the solvation free energy, is dominant and contributes to the stabilization of the zwitterionic form..
25. Tatsuya Aotake, Mitsuharu Suzuki, Naoki Aratani, Junpei Yuasa, Daiki Kuzuhara, Hironobu Hayashi, Haruyuki Nakano, Tsuyoshi Kawai, Jishan Wu, Hiroko Yamada, 9,9′-Anthryl-anthroxyl radicals
Strategic stabilization of highly reactive phenoxyl radicals, Chemical Communications, 10.1039/c4cc10104a, 51, 31, 6734-6737, 2015.04, Stable 9,9′-anthryl-anthroxyl radicals were synthesized and isolated, and the structures were fully characterized by single crystal X-ray diffraction analysis and ESR measurement. The resonance structure and steric protection of the peripheral positions and the most reactive 9-position of anthracene prolong the half-life of the radical in solution to 11 days. This journal is.
26. Tatsuya Aotake, Mitsuharu Suzuki, Naoki Aratani, Junpei Yuasa, Daiki Kuzuhara, Hironobu Hayashi, Haruyuki Nakano, Tsuyoshi Kawai, Jishan Wu, Hiroko Yamada, Erratum
9,9′-Anthryl-anthroxyl radicals: Strategic stabilization of highly reactive phenoxyl radicals (Chemical Communications (2015)), Chemical Communications, 10.1039/c5cc90112j, 51, 24, 2015.01.
27. Satoshi Omomo, Yasuhisa Maruyama, Ko Furukawa, Taniyuki Furuyama, Haruyuki Nakano, Nagao Kobayashi, Yoshihiro Matano, Optical, electrochemical, and magnetic properties of pyrrole- And thiophene-bridged 5,15-diazaporphyrin dimers, Chemistry - A European Journal, 10.1002/chem.201405482, 21, 5, 2003-2010, 2015.01, The first examples of pyrrole- and thiophenebridged 5,15-diazaporphyrin (DAP) dimers are prepared through Stille coupling reactions of nickel(II) and copper(II) complexes of 3-bromo-10,20-dimesityl-5,15-diazaporphyrin (mesityl = 2,4,6-trimethylphenyl) with the respective 2,5-bis-(tributylstannyl)heteroles. The effects of the heterole spacers and meso nitrogen atoms on the optical, electrochemical, and magnetic properties of the DAP dimers are investigated by UV/Vis absorption spectroscopy, density functional theory calculations, magnetic circular dichroism spectroscopy, cyclic voltammetry, and EPR spectroscopy. The heterole spacers are found to have a significant impact on the electronic transitions over the entire p-system. In particular, the pyrrolebridged DAP dimers exhibit high light-harvesting potential in the low-energy visible/near-infrared region owing to the intrinsic charge-transfer character of the lowest excitation..
28. Yoshihiro Matano, Yukiko Hayashi, Haruyuki Nakano, Hiroshi Imahori, N,S,P-hybrid donor-π-acceptor organic dyes for dye-sensitized solar cell
Synthesis, optical properties, and photovoltaic performances, Heteroatom Chemistry, 10.1002/hc.21188, 25, 6, 533-547, 2014.06, New donor-π-acceptor organic (D-π-A) dyes composed of triarylamine, oligothiophene, and phosphole subunits were prepared, and their optical and photovoltaic properties were investigated. The regioselective α-lithiation of the thiophene ring of 2-(thiophen-2-yl)phospholes bearing an ester group, followed by treatment with tributyltin chloride afforded 2-(5-(tributylstannyl)thiophen-2-yl)phosphole derivatives, which underwent Stille coupling with 5′-(p-(diarylamino)phenyl)-5-bromo-2,2′-bithiophene to give triarylamine-terthiophene-phosphole hybrid π systems bearing the terminal ester group. The alkaline hydrolysis of the ester group yielded the target dyes, bearing the carboxylic acid anchoring group. The UV-vis absorption spectra of the new N,S,P-hybrid dyes displayed broad and intense π-π∗ transitions with two absorptionmaxima in the visible region. Density functional theory (DFT) calculations of two dye models revealed that each highest occupied molecular orbital (HOMO) resides on the triarylamine-oligothiophene π network, whereas each lowest unoccupied molecular orbital (LUMO) is basically located on the phosphole subunit. In addition, the time-dependent DFT calculations of the models showed that the lowest energy bands of these hybrid dyes are mainly consisted of the HOMO-to-LUMO+1 and HOMO-to-LUMO transitions with the large intramolecular charge-transfer character. The N,S,P-hybrid-dye-sensitized TiO2 cells exhibitedmoderate power conversion efficiencies of up to 5.6%. The present findings corroborate the potential utility of the phosphole skeletons as the acceptor components in the D-π-A sensitizers..
29. Yoshihiro Matano, Daisuke Fujii, Tarou Shibano, Ko Furukawa, Tomohiro Higashino, Haruyuki Nakano, Hiroshi Imahori, Covalently linked 5,15-diazaporphyrin dimers
Promising scaffolds for a highly conjugated azaporphyrin π system, Chemistry - A European Journal, 10.1002/chem.201304626, 20, 12, 3342-3349, 2014.03, The first examples of β-β directly linked, acetylene-bridged, and butadiyne-bridged 5,15-diazaporphyrin dimers have been prepared by palladium-catalyzed coupling reactions of nickel(II) and copper(II) complexes of 3-bromo-10,20-dimesityl-5,15-diazaporphyrin (mesityl=2,4,6-trimethylphenyl). The effects of the linking modes and meso-nitrogen atoms on the structural, optical, electrochemical, and magnetic properties of the distributed π systems were investigated by using X-ray crystallography, UV/Vis absorption spectroscopy, DFT calculations, cyclic voltammetry, and ESR spectroscopy. Both the electronic and steric effects of the meso-nitrogen atoms play an important role in the highly coplanar geometry of the directly linked dimers. The direct β-β linkage produces enhanced π conjugation and electron-spin coupling between the two diazaporphyrin units..
30. Mitsuharu Suzuki, Tatsuya Aotake, Yuji Yamaguchi, Nao Noguchi, Haruyuki Nakano, Ken ichi Nakayama, Hiroko Yamada, Synthesis and photoreactivity of α-diketone-type precursors of acenes and their use in organic-device fabrication, Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 10.1016/j.jphotochemrev.2013.10.003, 18, 50-70, 2014.03, Acenes are highly promising p-type organic semiconductors, and have been the subject of intense studies. However, acenes are often low in solubility and stability, which poses major obstacles in the synthesis and processing of this class of compounds. In order to overcome the problem, a series of α-diketone-type acene precursors have been developed. These precursors are generally more soluble and stable than the corresponding acene compounds, and their quantitative conversion can be achieved simply by photoirradiation both in solution and in the solid state. Further, the irreversible photoinduced removal of the α-diketone unit can be used to alter the optoelectronic properties of fluorophores. This review overviews the synthesis and photochemical properties of α-diketone-type acene precursors, as well as their use as intermediates in preparation of large acenes or highly functionalized acene derivatives. Computational studies on the mechanism of α-diketone photolysis and the use of α-diketone derivatives in fabrication of organic devices are also summarized in this review..
31. Yukako Kasai, Norio Yoshida, Haruyuki Nakano, Theoretical analysis of salt effect on intramolecular proton transfer reaction of glycine in aqueous NaCl solution, Journal of Molecular Liquids, 10.1016/j.molliq.2014.02.013, 200, PA, 32-37, 2014.01, The salt effect on the intramolecular proton transfer reaction of glycine in aqueous NaCl solution was considered using the reference interaction-site model self-consistent field theory. The free energy profiles were computed for various salt concentrations. The set of profiles clearly showed that the free energy gap between the zwitterionic form (ZW) and the neutral form (NF) became larger as the NaCl concentration increased. The transition-state structure of the solute glycine approaches the NF structure, and the reaction barrier height is reduced. From the energy decomposition analysis of the free energy of solvation, we found that the changes in the solvation free energy are determined by the balance between the electronic distortion energy, the electrostatic interaction, the solvent reorganization, and the entropic effects caused by the NaCl addition. The salt effect of NaCl makes all the species associated with the reaction unstable; however, the destabilization of NFs caused by NaCl addition is stronger than that of ZWs. In the ZW, the penalty coming from the solvent reorganization and the entropic effects are compensated by the strong solute-solvent electrostatic interaction..
32. Shinya Fujishige, Yukio Kawashima, Norio Yoshida, Haruyuki Nakano, Three-dimensional reference interaction site model self-consistent field study of the electronic structure of [Cr(H2O)6] 3+ in aqueous solution, Journal of Physical Chemistry A, 10.1021/jp405876g, 117, 34, 8314-8322, 2013.08, The three-dimensional reference interaction-site model self-consistent- field (3D-RISM-SCF) method was applied to the electronic structure of hexahydrated chromium trication [Cr(H2O)6]3+ in aqueous solution. The 3D distribution around [Cr(H2O) 6]3+ showed 12 maximum density points arising from hydrogen bonds, as well as eight local maximum points at the hollow sites, in the second hydration shell. The 3D distribution function also indicated 20 local maximum sites in the third hydration shell. The low-lying excited states of vertical transitions were computed using time-dependent density functional theory (TD-DFT), including the electric field from the solvent. The electronic configurations and excitation energies calculated using DFT and 3D-RISM-SCF were very similar, although the orbital energies involved in the transition were rather different. The two lowest excited states (14T and 2 4T) were roughly assigned to the d-d transitions, and the third and fourth excited states (34T and 44T) were assigned to ligand-to-metal charge-transfer transitions. The computed excited energies were in good agreement with the experimental values..
33. Yuichi Tanaka, Norio Yoshida, Haruyuki Nakano, Solvent effect on excited states of merocyanines
A theoretical study using the RISM-SCF method, Chemical Physics Letters, 10.1016/j.cplett.2013.08.004, 583, 69-73, 2013.01, The solvent effect on the excited states of streptopolymethinemerocyanine (SPMC) was investigated using the RISM-SCF method. The magnitudes of the shifts in both the π-π* and n-π* excitation energies caused by solvation were water > methanol > acetonitrile. The analysis of the solvation structure showed that the difference in the interactions between SPMC and solvent molecules produced this order. The correlation between the chain length and the solvent effect on the excitation energy was also investigated. The results showed the excitation energy shift caused by solvation to be nearly equal regardless of the chain length..
34. Yoshihiro Matano, Tarou Shibano, Haruyuki Nakano, Yoshifumi Kimura, Hiroshi Imahori, Free base and metal complexes of 5,15-diaza-10,20-dimesitylporphyrins
Synthesis, structures, optical and electrochemical properties, and aromaticities, Inorganic chemistry, 10.1021/ic301835c, 51, 23, 12879-12890, 2012.12, The synthesis, structures, optical and electrochemical properties, and aromaticity of a series of 5,15-diaza-10,20-dimesitylporphyrins (M-DAP; M = Pb, H2, Ni, Pd, Pt, Zn; mesityl = 2,4,6-trimethylphenyl) are reported. Treatment of mesityl-substituted bis(5,5′-dibromodipyrrin) with sodium azide in the presence of lead(II) acetylacetonate afforded Pb-DAP, which was quantitatively converted to H2-DAP by acidolysis. The free base H2-DAP reacted with palladium(II), platinum(II), and zinc(II) salts to give Pd-DAP, Pt-DAP, and Zn-DAP, respectively. The crystal structures, optical and electrochemical properties, and aromaticities of these β-unsubstituted M-DAPs were comprehensively investigated by X-ray crystallography, UV-vis absorption/fluorescence spectroscopy, nanosecond flash photolysis, cyclic and differential pulse voltammetry, NMR spectroscopy, and density functional theory calculations. The obtained data show that replacement of the 5- and 15-methine carbons with nitrogen atoms alters the intrinsic properties of the porphyrin 18φ system as follows: (i) the coordination spheres at the N4 core become contracted while keeping high planarity; (ii) the Q bands are red shifted and largely intensified; (III) the electron-accepting ability is enhanced, whereas the electron-donating ability is reduced; (iv) the radiative decay rates from the S1 state are enhanced; and (v) the aromaticity of the 18φ circuit is slightly reduced in terms of both geometric and magnetic criteria. These optical and electrochemical properties of M-DAPs stem from their characteristic frontier orbitals; two HOMOs and two LUMOs are nondegenerate as a result of the incorporation of the electronegative nitrogen atoms at the two meso positions. In addition, the group 10 metals incorporated at the core finely tune the fundamental properties of DAP φ systems through inductive effects as well as dφ-pφ antibonding orbital interactions; the HOMO-LUMO gaps of the group 10 metal complexes increase in the order Ni-DAP < Pd-DAP < Pt-DAP..
35. Tetsuo Okujima, Tasuku Kikkawa, Haruyuki Nakano, Hiroshi Kubota, Nobumasa Fukugami, Noboru Ono, Hiroko Yamada, Hidemitsu Uno, Retro-Diels-Alder approach to the synthesis of π-expanded azuliporphyrins and their porphyrinoid aromaticity, Chemistry - A European Journal, 10.1002/chem.201201399, 18, 40, 12854-12863, 2012.10, Bicyclo[2.2.2]octadiene (BCOD) fused azuliporphyrins were synthesized by 3+1 porphyrin synthesis of azulitripyrranes with diformylpyrroles. Subsequent retro-Diels-Alder reaction of the BCOD-fused azuliporphyrins afforded azulibenzo-, azulidibenzo-, and azulitribenzoporphyrins 1-5. NMR and UV/Vis spectra, as well as nucleus-independent chemical shift (NICS) calculations revealed that 1-5 and their diprotonated dications exhibit relatively low porphyrinoid aromaticity, which was dependent on the position and number of fused benzene rings present. Porphyrins: A series of azulibenzoporphyrins were synthesized based on 3+1 porphyrin synthesis and retro-Diels-Alder reaction of bicyclo[2.2.2]octadiene-fused precursors (see scheme). UV/Vis spectra and NICS calculations revealed that their diprotonated dications exhibited a low porphyrinoid aromaticity from the porphyrinlike π circuit, which was dependent on the position and number of fused benzene rings..
36. Yoshihiro Matano, Tarou Shibano, Haruyuki Nakano, Hiroshi Imahori, Nickel(II) and copper(II) complexes of β-unsubstituted 5,15-diazaporphyrins and pyridazine-fused diazacorrinoids
Metal-template syntheses and peripheral functionalizations, Chemistry - A European Journal, 10.1002/chem.201200463, 18, 20, 6208-6216, 2012.05, The present paper reports the first comprehensive study on the synthesis, structures, optical and electrochemical properties, and peripheral functionalizations of nickel(II) and copper(II) complexes of β-unsubstituted 5,15-diazaporphyrins (M-DAP; M=Ni, Cu) and pyridazine-fused diazacorrinoids (Ni-DACX; X=N, O). These two classes of compounds were constructed starting from mesityldipyrromethane by a metal-template method. Ni-DAP and Cu-DAP were prepared in high yields by the reaction of the respective metal-bis(dibromodipyrrin) complexes with NaN 3-CuX (X=I, Br), whereas Ni-DACN and Ni-DACO were formed as predominant products by the reaction with NaN 3. In both cases, the metal centers change their geometry from tetrahedral to square planar during the aza-annulation; X-ray crystallographic analyses of M-DAPs showed highly planar diazaporphyrin π planes. The Q band of Ni-DAP was redshifted and intensified compared with that of a nickel-porphyrin reference, due to the involvement of electronegative nitrogen atoms at the meso positions. It was found that the peripheral bromination of Ni-DAP and Ni-DACO occurred regioselectively to afford Ni-DAP-Br 4 and Ni-DACO-Br, respectively. These brominated derivatives underwent Stille reactions with tributyl(phenyl)stannane to give the corresponding phenylated derivatives, Ni-DAP-Ph 4 and Ni-DACO-Ph. On the basis of the absorption spectra and X-ray analysis, it has been concluded that the attached phenyl groups efficiently conjugate with the diazaporphyrin π system. The present results unambiguously corroborate that the β-unsubstituted DAPs and DACXs are promising platforms for the development of a new class of π-conjugated azaporphyrin-based materials..
37. Yukio Kawashima, Satoshi Yamamoto, Tetsuya Sakata, Haruyuki Nakano, Katsura Nishiyama, Ryo Akiyama, Solvent effect on the fluorescence spectra of coumarin 120 in water
A combined quantum mechanical and molecular mechanical study, journal of the physical society of japan, 10.1143/JPSJS.81SA.SA024, 81, SUPPL. A, 2012.01, The solvent effect on the steady-state and time-resolved fluorescence spectra of coumarin 120 in water was studied utilizing a molecular dynamics simulation with combined quantum mechanical/molecular mechanical method. The constructed steady-state fluorescence spectra reproduced the Stokes shift of the experimental data. The solvent effects on the spectra were examined by constructing three different spectra: spectra using the entire system, spectra including water molecules only in the first solvent shell, and spectra excluding all water molecules. We found that the variation in C-C bond length makes the largest contribution to the solvent shift in the fluorescence spectrum, which indicates the importance of the electronic structure variation..
38. Yukio Kawashima, Haruyuki Nakano, Jaewoon Jung, Seiichiro Ten-Nod, A combined quantum mechanical and molecular mechanical method using modified generalized hybrid orbitals
Implementation for electronic excited states, Physical Chemistry Chemical Physics, 10.1039/c1cp20438f, 13, 24, 11731-11738, 2011.06, The generalized hybrid orbital (GHO) method is implemented at the second-order approximate coupled cluster singles and doubles (CC2) level for quantum mechanical (QM)/molecular mechanical (MM) electronic excited state calculations. The linear response function of CC2 in the GHO scheme is derived and implemented. The new implementation is applied to the first singlet excited states of three aromatic amino acids, phenylalanine, tyrosine, and tryptophan, and also bacteriorhodopsin for assessment. The results obtained for aromatic amino acids agreed well with the full QM CC2 calculations, while the calculated excitation energies of bacteriorhodopsin and its chromophore, all-trans retinal, reproduced the environmental shift of the experimental data. For the bacteriorhodopsin case, the environmental shift of GHO also showed good agreements with the experimental data. The contribution of the quantum effect of certain moieties in the excited states is elucidated by changing the partitioning of QM and MM regions..
39. R. Ebisuzaki, Y. Watanabe, Y. Kawashima, and H. Nakano, Parallel implementation of the four-commponent relativistic quasidegenerate perturbation theory with general multiconfigurational reference functions, J. Chem. Theory Comp., 10.1021/ct2000205, 7, 998-1005, 2011.04.
40. S. Suzuki, R. Ebisuzaki, Y. Kawashima, Y. Watanabe, H. Nakano, Efficient and Accurate Approximation to Relativistic Multireference Perturbation Theory, Kyushu University Global-COE program, Science for Future Molecular Systems, Journal, 5, 41-43, 2011.04.
41. Hisako Sato, Hidemitsu Uno, Haruyuki Nakano, Identification of geometrical isomers using vibrational circular dichroism spectroscopy
A series of mixed-ligand complexes of diamagnetic Co(III) ions, Dalton Transactions, 10.1039/c0dt01342k, 40, 6, 1332-1337, 2011.02, Vibrational circular dichroism (VCD) spectra were measured on the chloroform solutions of a series of mixed-ligand diamagnetic Co(iii) complexes, [Co(tfac)n(acac)3-n] (n = 0-3, tfac = 1,1,1-trifluoro-2,4- pentanedionato; acac = acetylacetonato). Distinct differences were observed in the VCD spectra among the geometrical isomers of the same ligand composition. Such differentiation was hardly possible by their infra-red spectra alone. The structural identification of these isomers was performed in conjunction with DFT calculations..
42. T. Sakata, Y. Kawashima, and H. Nakano, Solvent effect on the absorption spectra of coumarin 120 in water: A combined quantum mechanical and molecular mechanical study, J. Chem. Phys., 10.1063/1.3506616, 134, 014501/1-11, 2011.01.
43. T. Sakata, Y. Kawashima, and H. Nakano, Low-Lying Excited States of C120 and C151: A Multireference Perturbation Theory Study, J. Phys. Chem. A, 10.1021/jp1019872, 114, 12363-12368, 2010.12.
44. Yoshihiro Watanabe, Haruyuki Nakano, Hiroshi Tatewaki, Effect of removing the no-virtual pair approximation on the correlation energy of the He isoelectronic sequence. II. Point nuclear charge model, Journal of Chemical Physics, 10.1063/1.3359857, 132, 12, 2010.04, The correlation energies (CEs) of the He isoelectronic sequence Z=2-116 with a point nuclear charge model were investigated with the four component relativistic configuration interaction method. We obtained CEs with and without the virtual pair approximation which are close to the values from Pestka 's Hylleraas-type configuration interaction calculation. We also found that the uniform charge and point charge models for the nucleus differ substantially for Z≥100..
45. Hiroko Moriyama, Yoshihiro Watanabe, Haruyuki Nakano, Shigeyoshi Yamamoto, Hiroshi Tatewaki, Electronic structure of LaO based on frozen-core four-component relativistic multiconfigurational quasidegenerate perturbation theory, Journal of Chemical Physics, 10.1063/1.3359854, 132, 12, 2010.04, The electronic structure of the LaO molecule is studied using frozen-core four-component multiconfigurational quasidegenerate perturbation theory. The ground state and nine experimentally observed excited states are examined. The ground state is 2σ21/2+ and its gross atomic orbital population is La (5 p5.76 6s0.83 6 p0.14 p *0.21 d *1.17 f *0.26) O (2 p4.63), where p*, d*, and f* are the polarization functions of La that form molecular spinors with O 2ps. We found that it is not necessary to consider the excitation from the O 2p electrons when analyzing the experimental spectra. This validates the foundation of the ligand field theory on diatomic molecules, including the La atom where only one electron is considered. The spectroscopic constants Re, ωe, and T0 calculated for the ground state and low-lying excited states A′ (Δ23/2), A′ (Δ2 5/2) A (Π2 1/2), and A (Π2 3/2) are in good agreement with the experimental values..
46. Takashi Nakabuchi, Makoto Nakashima, Shinya Fujishige, Haruyuki Nakano, Yoshihiro Matano, Hiroshi Imahori, Synthesis and reactions of phosphaporphyrins
Reconstruction of π-skeleton triggered by oxygenation of a core phosphorus atom, Journal of Organic Chemistry, 10.1021/jo902060b, 75, 2, 375-389, 2010.01, (Chemical Equation Presented) The synthesis, structures, optical and redox properties, and reactivity of phosphaporphyrins are reported. The 21-phosphaporphyrin (P,N3-porphyrin) and 23-phospha-21-thiaporphyrin (P,S, N2-porphyrin) were prepared via acid-promoted dehydrative condensation between a phosphatripyrrane and the corresponding 2,5-bis[hydroxy(phenyl)methyl]heteroles followed by 2,3-dichloro-5,6- dicyanobenzoquinone oxidation. Experimental (NMR, UV-vis, and X-ray analyses) and theoretical (DFT calculations) results suggest that the 18π aromaticity inherent in regular N4-porphyrins was maintained in these phosphaporphyrins. X-ray crystallography revealed a slightly distorted 18π aromatic ring for the P,N3-porphyrin with the phosphole and three pyrrole rings tilted from the 24-atoms mean plane by 9.6° and 3.8-15.4°, respectively. DFT calculations on model compounds showed that the P,X,N2-porphyrins (X = N, S) possess considerably small HOMO-LUMO gaps as compared with N 4- and S,N3-porphyrins, which is reflected in the red-shifted absorptions, low oxidation potentials, and high reduction potentials of the phosphaporphyrins. The P-oxygenation of the P,X,N2-porphyrins with H2O2 has been found to lead to the formation of different types of products. The 18π P,N3-porphyrin was transformed into the 22π aromatic P(O), N3-porphyrin accompanied by the π extension at the peripheral C3 bridge, whereas the 18π P,S,N2-porphyrin was converted to the isophlorin-type 20π antiaromatic P(O),S,N2-porphyrin. In both of the reactions, simple P-oxygenated 18π P(O),X,N2-porphyrins were formed as the initial products, which were subsequently transformed into the 22π or 20π porphyrins. The two reaction courses from 18π to 20π/22π are apparently determined by the combination of the core heteroatoms (i.e., P,N3 or P,S,N2) and the structure of the peripherally fused carbocycles. The present results demonstrate that the incorporation of a phosphorus atom into the core is not only a highly promising way to modify the fundamental properties of the porphyrin 18π system but also a reliable tool to stabilize uncommon 22π and 20π systems through the chemical modifications at the core phosphorus atom..
47. T. Sakata, Y. Kawashima, and H. Nakano, New Sampling Scheme for Combined Quantum Mechanical and Molecular Mechanical Simulation, Kyushu University Global-COE program, Science for Future Molecular Systems, Journal, 3, 13-20, 2009.12.
48. Tetsuya Sakata, Yukio Kawashima, Haruyuki Nakano, Low-lying excited states of 7-aminocoumarin derivatives
A theoretical study, International Journal of Quantum Chemistry, 10.1002/qua.22019, 109, 9, 1940-1949, 2009.07, Excited states of three 7-aminocoumarin derivatives, coumarin 120 (7- amino-4-methylcoumarin), pyrrolyl coumarin 7-(1H-pyrrol-1-yl)-4-methyl-2H-1- benzopyran-2-one, and carbazole-coumarin hybrid 10H-4-methyl-2H-2-oxopyrano[5,6- b]carbazole, have been studied using B3LYP time-dependent density functional theory (TDDFT). The solvent effect has been taken into account using the polarizable continuum model. The spectra calculated using TDDFT agree well with the experimental absorption spectra. The electronic structures and the solvent effect for the low-lying singlet excited states have been investigated. The HOMO of the pyrrolyl coumarin is localized on the pyrrolyl ring, while the HOMO in the other 7- aminocoumarins is delocalized over the entire molecule. This leads to the weak fluorescence of the pyrrolyl coumarins found in experiments. The HOMO and next HOMO in carbazole-coumarin hybrids have similar orbital energy values, which is not the case in the other 7-aminocoumarin derivatives. This leads to the additional peaks found in the 30,000-40,000 cm-1 region of the observed absorption spectra, which are specific for carbazole-coumarin hybrids..
49. Hiroko Moriyama, Hiroshi Tatewaki, Yoshihiro Watanabe, Haruyuki Nakano, Molecular spinors suitable for four-component relativistic correlation calculations
Studies of LaF+ and LaF using multiconfigurational quasi-degenerate perturbation theory, International Journal of Quantum Chemistry, 10.1002/qua.22013, 109, 9, 1898-1904, 2009.07, Multiconfigurational second-order quasidegenerate perturbation theory (MCQDPT) calculations were performed for the LaF+ molecule, with one LaF2+ and four LaF+ Dirac-Fock-Roothaan (DFR) spinor sets. The best spinor set was that of LaF2+, which gave the lowest total energies and also the best excitation energies for any state considered. The MCQDPT calculations with the cation and neutral molecular spinors were also performed for LaF. The MCQDPT with the cation spinors gave the lowest total energies for all states under consideration, and the calculated excitation energies compared best with experiment. We prefer the LaF+ spinor set to those of LaF. These calculations indicate that the DFR spinor set for the (n-1) electron system is adequate for treating the molecular electronic system having n electrons..
50. Nao Noguchi, Haruyuki Nakano, Valence-bond description of chemical reactions on Born-Oppenheimer molecular dynamics trajectories, Journal of Chemical Physics, 10.1063/1.3116787, 130, 15, 2009.05, The nature of chemical bonds on dynamic paths was investigated using the complete active space valence-bond (CASVB) method and the Born-Oppenheimer dynamics. To extract the chemical bond picture during reactions, a scheme to collect contributions from several VB (resonance) structures into a small numbers of indices was introduced. In this scheme, a tree diagram for the VB structures is constructed with the numbers of the ionic bonds treated as generation. A pair of VB structures is related to each other if one VB structure is transferred into the other by changing a covalent bond to an ionic bond. The former and latter VB structures are named parent and child structures, respectively. The weights of the bond pictures are computed as the sum of the CASVB occupation numbers running from the top generation to the bottom along the descent of the VB structures. Thus, a number of CASVB occupation numbers are collected into a small number of indices, and a clear bond picture may be obtained from the CASVB wave function. The scheme was applied to the hydrogen exchange reaction H2 +F→H+HF and the Diels-Alder reaction C 5 H 6 (cyclopentadiene) + CH 2 = CH 2 (ethylene) → C 7 H 10 (norbornene). In both the reactions, the scheme gave a clear picture for the Born-Oppenheimer dynamics trajectories. The reconstruction of the bonds during reactions was well described by following the temporal changes in weight..
51. Yoshihiro Matano, Takashi Nakabuchi, Shinya Fujishige, Haruyuki Nakano, Hiroshi Imahori, Redox-coupled complexation of 23-phospha-21-thiaporphyrin with group 10 metals
A convenient access to stable core-modified isophlorin-metal complexes, Journal of the American Chemical Society, 10.1021/ja807742g, 130, 49, 16446-16447, 2008.12, Core-modified isophlorin-metal complexes were successfully prepared by redox-coupled complexation of P,S,N2-hybrid porphyrin with zerovalent palladium, nickel, and platinum. In this transformation, the core-phosphorus atom plays crucial roles in enhancing the electron-accepting ability of the 18π porphyrin ring and stabilizing the 20π isophlorin ring owing to high P-M affinity. The isolated Pd and Pt complexes are chemically stable under ambient conditions. The Pd-P,S,N2 isophlorin complex was structurally characterized by X-ray crystallography, which revealed a distorted 20π plane with a square planar palladium(II) center. Experimental (1H, UV-vis, and X-ray) and theoretical (density functional theory calculations) results suggest that the P,S,N2-isophlorin-metal complexes possess nonaromaticity in terms of both magnetic and geometrical criteria..
52. Hiroshi Tatewaki, Shigeyoshi Yamamoto, Yoshihiro Watanabe, Haruyuki Nakano, Electronic structure of CeF from frozen-core four-component relativistic multiconfigurational quasidegenerate perturbation theory, Journal of Chemical Physics, 10.1063/1.2924118, 128, 21, 2008.06, We have investigated the ground state and the two lowest excited states of the CeF molecule using four-component relativistic multiconfigurational quasidegenerate perturbation theory calculations, assuming the reduced frozen-core approximation. The ground state is found to be (4 f1) (5 d1) (6 s1), with =3.5, where is the total electronic angular momentum around the molecular axis. The lowest excited state with =4.5 is calculated to be 0.104 eV above the ground state and corresponds to the state experimentally found at 0.087 eV. The second lowest excited state is experimentally found at 0.186 eV above the ground state, with =3.5 based on ligand field theory calculations. The corresponding state having =3.5 is calculated to be 0.314 eV above the ground state. Around this state, we also have the state with =4.5. The spectroscopic constants Re, ωe, and (1-0) calculated for the ground and first excited states are in almost perfect agreement with the experimental values. The characteristics of the CeF ground state are discussed, making comparison with the La F+ and LaF molecules. We denote the d - and f -like polarization functions as d* and f*. The chemical bond of CeF is constructed via { Ce3.6+ (5 p6 d*0.3 f*0.1) F0.6- (2 p5.6) }3+ formation, which causes the three valence electrons to be localized at Ce3.6+..
53. Hiroko Moriyama, Yoshihiro Watanabe, Haruyuki Nakano, Hiroshi Tatewaki, Electronic structure of LaF+ and LaF from frozen-core four-component Relativistic multiconfigurational quasidegenerate perturbation theory, Journal of Physical Chemistry A, 10.1021/jp7096197, 112, 12, 2683-2692, 2008.03, The electronic structure of the molecules LaF+ and LaF was studied using frozen-core four-component multiconfigurational quasidegenerate perturbation theory. To obtain proper excitation energies for LaF+, it was essential to include electronic correlations between the outermost valence electrons (4f, 5d, and 6s) and ionic core electrons composed of (4s, 4p, 4d, 5s, and 5p). The lowest-lying 16 excited states were examined for LaF +, and the lowest 30 states were examined for LaF. The excitation energies calculated for LaF+ agree with the available experimental values, as well as with values from ligand field theory. Errors are within 0.4 eV; for example, the highest observed state 2Π is 3.77 eV above the ground state, and the present value is 4.09 eV. For LaF, agreement between the experimental and theoretical state assignments and between the experimental and calculated excitation energies was generally good, except for the electron configurations of certain states. Errors are within 0.4 eV except for a single anomaly; for example, the highest observed excited-state discussed in this work is 2.80 eV above the ground state, and the present value is 2.42 eV. We discuss the characteristics of the bonding in LaF+ and LaF..
54. Yoshihiro Matano, Makoto Nakashima, Takashi Nakabuchi, Hiroshi Imahori, Shinya Fujishige, Haruyuki Nakano, Monophosphaporphyrins
Oxidative π-extension at the peripherally fused carbocycle of the phosphaporphyrin ring, Organic Letters, 10.1021/ol7029118, 10, 4, 553-556, 2008.02, The 18π-σ3- and 22π-σ4- phosphaporphyrins were successfully prepared by an acid-promoted condensation between a phosphatripyrrane and a 2,5-bis[hydroxy(phenyl)methyl]pyrrole, and their structures, aromaticity, and optical and electrochemical properties were disclosed. Notably, a σ4-phosphaporphyrinogen and the 18π-σ3-phosphaporphyrin undergo oxidative π-extension at the peripherally fused carbocycle to afford the 22π-σ4- phosphaporphyrin..
55. J. Saito, K. Ara, K. Sugiyama, H. Kitagawa, H. Nakano, K. Ogata, N. Yoshioka, Study on Chemical Reactivity Control of Liquid Sodium - Development of Nano-Fluid and its Property, and Applicability to FBR Plant, ICONE16: Proceeding of the 16th International Conference on Nuclear Engineering, 1, 559-563, 2008.01.
56. Yoshihiro Matano, Tomonori Shinokura, Kazuaki Matsumoto, Hiroshi Imahori, Haruyuki Nakano, Synthesis and aggregation behavior of meso-sulfinylporphyrins
Evaluation of S-chirality effects on the self-organization to S-oxo-tethered cofacial porphyrin dimers, Chemistry - An Asian Journal, 10.1002/asia.200700191, 2, 11, 1417-1429, 2007.11, The synthesis and aggregation behavior of meso-sulfinylporphyrins are described. The copper-catalyzed C-S cross-coupling reaction of a meso-iodoporphyrin with benzenethiol and n-octanethiol has proved to be an efficient method for the synthesis of meso-sulfanylporphyrins, which are oxygenated by m-chloroperbenzoic acid to produce the corresponding meso-sulfinylporphyrins. Optically active zinc meso-sulfinylporphyrins were successfully isolated by means of optical resolution of the racemates on a chiral HPLC column. Zinc sulfinylporphyrins readily undergo self-organization through S-oxo-zinc coordination to form cofacial porphyrin dimers in solution, in which the hetero- and homodimers are present as a diastereomeric mixture. The aggregation modes of the S-oxo-tethered porphyrin dimers were fully characterized by 1H NMR, IR, and UV/Vis spectroscopy as well as DFT calculations on their model compounds, thus revealing that the self-aggregation behavior depends on the combination of S chirality. The absolute configurations at the sulfur center can be determined by the exciton-coupled CD method. The observed self-association constant for the S-oxo-tethered dimerization of (S)-phenylsulfinylporphyrin in toluene is larger than that in dichloromethane, which reflects the difference in dipole moments between the homodimer and the monomer. In cyclic and differential pulse voltammetry, the first oxidation process of the cofacial dimers is split into two reversible steps, which indicates that the initially produced π radical cations are delocalized efficiently between the two porphyrin rings. The present findings demonstrate the potential utility of meso-sulfinyl groups as promising ligands for investigating the effects of peripheral chirality on the structures and optical and electrochemical properties of metal-assisted porphyrin self-assemblies..
57. Xuan Zhang, Yusuke Komoto, Kenji Sakota, Nakagaki Masayuki, Teruo Shinmyozu, Shinkoh Nanbu, Haruyuki Nakano, Hiroshi Sekiya, Remarkable suppression of the excited-state double-proton transfer in the 7-azaindole dimer due to substitution of the dimethylamino group studied by electronic spectroscopy in the gas phase, Chemical Physics Letters, 10.1016/j.cplett.2007.06.077, 443, 4-6, 194-198, 2007.08, The fluorescence excitation and dispersed fluorescence spectra of jet-cooled 4-dimethylamino-7-azaindole dimer are recorded to investigate the effect of a substitution of a dimethylamino group into the 4-position of the hydrogen atom of the 7-azaindole on the excited-state double proton transfer (ESDPT). The substitution of the dimethylamino group drastically suppresses the ESDPT reaction..
58. Ryo Ebisuzaki, Yoshihiro Watanabe, Haruyuki Nakano, Efficient implementation of relativistic and non-relativistic quasidegenerate perturbation theory with general multiconfigurational reference functions, Chemical Physics Letters, 10.1016/j.cplett.2007.05.066, 442, 1-3, 164-169, 2007.07, An efficient computational scheme for using the relativistic and non-relativistic quasidegenerate perturbation theory with general multiconfigurational reference functions is implemented. The scheme is based on the matrix element between the reference and the zero- to two-electron ionized determinants. Comparison with a previous scheme based on diagrams is made using the excitation spectra of [PtCl4]2-, CH3I, and H2CO as examples, and the efficiency of the scheme is illustrated..
59. Xuan Zhang, Yusuke Komoto, Kenji Sakota, Masayuki Nakagaki, Haruyuki Nakano, Teruo Shinmyozu, Hiroshi Sekiya, Heavy mass effect on excited-state double-proton transfer in the 7-azaindole dimer by Cl substitution, Chemical Physics Letters, 10.1016/j.cplett.2007.05.004, 441, 4-6, 176-180, 2007.06, The measurement of the electronic spectra of jet-cooled 4-chloro-7-azaindole dimer (4CAI2) revealed that the Cl substitution substantially suppresses the excited-state double-proton transfer (ESDPT). Quantum chemistry calculation at the CIS level suggested that the change in the intermolecular stretching mode, which promotes ESDPT, is important for the suppression of ESDPT..
60. Yoshihiro Watanabe, Haruyuki Nakano, Hiroshi Tatewaki, Effect of removing the no-virtual-pair approximation on the correlation energy of the He isoelectronic sequence, Journal of Chemical Physics, 10.1063/1.2733647, 126, 17, 2007.05, The correlation energies (CEs) for the He-like ions are studied with the virtual-pair approximation (VPA) and with the no-virtual-pair approximation (NVPA). In contrast to the nonrelativistic CEs, the CEs calculated with relativity fell sharply as the nuclear charge Z increased, although the CE calculated with the NVPA was considerably lower than with the VPA for the heavier atoms. It is shown that CE calculated with a Hylleraas-type function implicitly includes the effects of the excitations into negative-energy states, which corresponds to the VPA. The present results verify that the strong dependence on Z of the CE of He-like ions is an essential effect of the relativity..
61. Yoshihiro Matano, Takashi Nakabuchi, Tooru Miyajima, Hiroshi Imahori, Haruyuki Nakano, Synthesis of a phosphorus-containing hybrid porphyrin, Organic Letters, 10.1021/ol0622763, 8, 25, 5713-5716, 2006.12, (Diagram presented) A phosphorus-containing hybrid porphyrin was successfully prepared via the BF3-promoted dehydrative condensation between σ4-phosphatripyrrane and 2,5-bis[hydroxy(phenyl)methyl] thiophene. The NMR and UV-vis absorption spectra, electrochemical measurements, and DFT calculations revealed that the σ3-P,N 2,S-hybrid porphyrin exhibits high aromaticity as an 18π-electron system in terms of both geometric and magnetic criteria..
62. H. Nakano, Multireference Perturbation Theory with Four-Component General Multiconfigurational Reference Functions, Recent Progress in Computational Sciences and Engineering, 7, 931-934, 2006.10.
63. Masayuki Nakagaki, Eriko Nishi, Kenji Sakota, Haruyuki Nakano, Hiroshi Sekiya, A model two-dimensional potential for internal rotation of 9-methylanthracene studied by electronic spectroscopy and DFT calculations, Chemical Physics, 10.1016/j.chemphys.2006.06.043, 328, 1-3, 190-196, 2006.09, The S1-S0 fluorescence excitation and dispersed fluorescence spectra of 9-methylanthracene are measured in a supersonic free jet expansion. Several low-frequency bands assigned to the transitions between the internal rotational levels of the methyl group can not be fitted to the calculated energy levels obtained by the one-dimensional rotor model. We have introduced a two-dimensional model incorporating the coupling of the methyl rotation and an out-of-plane bending motion of the anthracene ring. The calculations based on this model reproduce the intensity distributions in the fluorescence excitation and dispersed fluorescence spectra as well as the frequencies of the internal rotational levels in the S0 and S1 state..
64. Shigeyoshi Yamamoto, Hiroshi Tatewaki, Hiroko Moriyama, Haruyuki Nakano, A study of the ground state of manganese dimer using quasidegenerate perturbation theory, Journal of Chemical Physics, 10.1063/1.2178798, 124, 12, 2006.04, We study the electronic structure of the ground state of the manganese dimer using the state-averaged complete active space self-consistent field method, followed by second-order quasidegenerate perturbation theory. Overall potential energy curves are calculated for the 1g+, 11u+, and 11Πu states, which are candidates for the ground state. Of these states, the 1g+ state has the lowest energy and we therefore identify it as the ground state. We find values of 3.29 Å, 0.14 eV, and 53.46 cm-1 for the bond length, dissociation energy, and vibrational frequency, in good agreement with the observed values of 3.4 Å, 0.1 eV, and 68.1 cm-1 in rare-gas matrices. These values show that the manganese dimer is a van der Waals molecule with antiferromagnetic coupling..
65. Makoto Miyajima, Yoshihiro Watanabe, Haruyuki Nakano, Relativistic quasidegenerate perturbation theory with four-component general multiconfiguration reference functions, Journal of Chemical Physics, 10.1063/1.2161182, 124, 4, 2006.02, Relativistic quasidegenerate perturbation theory (QDPT) using general multiconfiguration (GMC) reference functions is developed and implemented. It is the relativistic counterpart of the nonrelativistic QDPT with GMC reference and thus retains all the advantages of the nonrelativistic GMC reference QDPT, such as applicability to any configuration space and small computational cost compared to the complete configuration-space case. The method is applied to the potential-energy curves of the ground states of I2 and Sb2 molecules, the excitation energies of CH3 I, and the energies of the lowest terms of C, Si, and Ge atoms, and is shown to provide a balanced description of potential-energy curves and accurate transition energies for systems containing heavy elements and to provide much better results compared to the reference function (i.e., active space configuration interaction) level..
66. M. Nakagaki, E. Nishi, K. Sakota, K. Nishi, H. Nakano, H. Sekiya, Internal rotation of methyl group in 2- and 1-methylanthracene studied by electronic spectroscopy and DFT calculations, Chem. Phys., 10.1016/j.chemphys.2005.06.006, 316, 1-3, 178-184, 316, 178-184, 2005.07.
67. H. Sato, A. Yamagishi, J. Yoshida, H. Nakano, and N. Hoshino, A Microscopic Model for Helical Twisting Power by the Optical Isomers of an Octahedral Metal Complex, Jpn. J. Appl. Phys., 10.1143/JJAP.44.4067, 44, 6A, 4067-4072, 44, 4067-4072, 2005.01.
68. Yuka Kobayashi, Nobuo Tajima, Haruyuki Nakano, Kimihiko Hirao, Selective catalytic reduction of nitric oxide by ammonia
The activation mechanism, Journal of Physical Chemistry B, 10.1021/jp047957z, 108, 33, 12264-12266, 2004.08, The activation mechanism of NH3 in the selective catalytic reduction of NO by NH3 on a V2O7H4 cluster was investigated using a complete active space self-consistent field method. Because of the easy bond dissociation of NH4+ adsorbed on Brønsted acid sites of the V2O5 configuration, the radical species NH3+ can occur with an activation energy of only 26.7 kcal/mol. The highly active intermediate NH 3+ is stabilized by forming a very strong hydrogen bond of approximately 29.2 kcal/mol to the vanadyl oxygen. This stabilization mechanism is very similar to the low-barrier hydrogen bond in the transition state, or in an unstable intermediate state, which has been reported for some enzymatic reactions..
69. Yuki Kurashige, Haruyuki Nakano, Kimihiko Hirao, The Most Stable Structure of SiC3 Studied by Multireference Perturbation Theory with General Multiconfiguration Self-Consistent Field Reference Functions, Journal of Physical Chemistry A, 10.1021/jp031133k, 108, 15, 3064-3067, 2004.04, The most stable structure of the SiC3 molecule has been investigated using second-order perturbation theory with general multiconfiguration self-consistent field reference functions (GMC-PT) and Dunning's augmented correlation-consistent polarized valence quadruple-ζ (aug-cc-pVQZ) basis set. The results showed that a closed-shell rhomboidal C isomer with a C-C transannular bond (2s) was most stable. Another closed-shell rhomboidal C isomer with a Si-C transannular bond (3s) and a linear triplet Si-C-C-C isomer (1t) was less stable by 5.3 and 6.7 kcal/mol, respectively, at the geometries optimized by the coupled cluster singles, doubles, and perturbative triples (CCSD(T)) method and the correlation-consistent polarized core-valence quadruple-zeta; (cc-pCVQZ) basis set, and by 9.0 and 9.9 kcal/mol, respectively, at the geometries optimized by the fully optimized reaction space self-consistent field (FORS-SCF) method and the 6-31G(d) basis set..
70. Y. Kurashige, H. Nakano, Y. Nakao, and K. Hirao, The pi->pi* excited states of long linear polyenes studied by the CASCI-MRMP method, Chem. Phys. Lett., 10.1016/j.cplett.2004.10.141, 400, 4-6, 425-429, 400, 425-429, 2004.01.
71. Y. Matano, H. Nomura, T. Hisanaga, H. Nakano, M. Shiro, and H. Imahori, Diverse Structures and Remarkable Oxidizing Ability of Triarylbismuthane Oxides. Comparative Study on the Structure and Reactivity of a Series of Triarylpnictogen Oxides, Organometallics, 10.1021/om0494115, 23, 23, 5471-5480, 23, 5471-5480, 2004.01.
72. Kazushi Sorakubo, Takeshi Yanai, Kenichi Nakayama, Muneaki Kamiya, Haruyuki Nakano, Kimihiko Hirao, A non-orthogonal Kohn-Sham method using partially fixed molecular orbitals, Theoretical Chemistry Accounts, 10.1007/s00214-003-0477-8, 110, 5, 328-337, 2003.12, A density functional theory method using partially fixed molecular orbitals (PFMOs) is presented. The PFMOs, which have some fixed molecular orbital coefficients and are non-orthogonal, are a generalization of the extreme localized orbitals (ELMOs) of Couty, Bayse, and Hall (1997) Theor Chem Acc 97:96. A non-orthogonal Kohn-Sham method with these PFMOs is derived, and is applied to molecular calculations on the ionization potential of pyridine, the energy difference between cis- and trans-butadiene, the reaction barrier height of the cyclobutene-cis-butadiene interconversion, and the potential energy curve of the hydrogen shift reaction of hydroxycarbene to formaldehyde. The PFMO Kohn-Sham method reproduces well the results of the full Kohn-Sham method without having a restriction on the molecular orbital coefficients. The difference is less than 0.1 eV in the ionization potential and about 0.1 kcal/mol in the barrier height and in the potential energy calculations..
73. Takeshi Yanai, Haruyuki Nakano, Takahito Nakajima, Takao Tsuneda, So Hirata, Yukio Kawashima, Yoshihide Nakao, Muneaki Kamiya, Hideo Sekino, Kimihiko Hirao, UTChem - A program for ab initio quantum chemistry, Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2660, 84-95, 2003.12, UTChem is a quantum chemistry software developed by Hirao's group at the University of Tokyo. UTChem is a research product of our work to develop new and better theoretical methods in quantum chemistry..
74. Kotaro Yokoyama, Haruyuki Nakano, Kimihiko Hirao, James P. Finley, Maximum radius of convergence perturbation theory
Test calculations on Be, Ne, H2 and HF, Theoretical Chemistry Accounts, 10.1007/s00214-003-0473-z, 110, 3, 185-189, 2003.10, Maximum radius of convergence (MAXRc) perturbation theory [(2000) Journal of Chemical Physics 112:6997] is tested on the beryllium and neon atoms using calculations that are truncated in high orders. Calculations are also performed on the ground-state potential-energy curves of H2 and HF. The neon atom calculations use the 3-21G basis set with added diffuse s and p functions. All other calculations use the STO-3G minimum basis set. MAXRc perturbation theory consistently performs well. The Epstein-Nesbet and Møller-Plesset perturbative expansions frequently diverge or exhibit slow convergence compared to the expansions obtained from MAXRc..
75. Henryk A. Witek, Haruyuki Nakano, Kimihiko Hirao, Multireference perturbation theory with optimized partitioning. II. Applications to molecular systems, Journal of Computational Chemistry, 10.1002/jcc.10311, 24, 12, 1390-1400, 2003.09, The second-order multireference perturbation theory using an optimized partitioning, denoted as MROPT(2), is applied to calculations of various molecular properties - excitation energies, spectroscopic parameters, and potential energy curves - for five molecules: ethylene, butadiene, benzene, N2, and O2. The calculated results are compared with those obtained with second- and third-order multireference perturbation theory using the traditional partitioning techniques. We also give results from computations using the multireference configuration interaction (MRCI) method. The presented results show very close resemblance between the new method and MRCI with renormalized Davidson correction. The accuracy of the new method is good and is comparable to that of second-order multireference perturbation theory using Møller-Plesset partitioning..
76. Hisako Sato, Akihiro Morita, Kanta Ono, Haruyuki Nakano, Noboru Wakabayashi, Akihiko Yamagishi, Templating effects on the mineralization of layered inorganic compounds
(1) Density functional calculations of the formation of single-layered magnesium hydroxide as a brucite model, Langmuir, 10.1021/la034546l, 19, 17, 7120-7126, 2003.08, This work aims at understanding the formation and stability of a layered structure of brucite mineral [Mg(OH)2] via density functional calculations. Because Mg-O-Mg bond formation from a hydrolyzed species of Mg(II) ion is a critical elemental step of mineralization, we studied the reaction mechanism of Mg-O-Mg linkage using a model cluster, [Mg(OH)2] n (n = 1-10), in the gas phase and a water solution. The results indicate that no barrier exists during the reaction path from [Mg(OH) 2]n-1 + Mg(OH)2 to [Mg(OH)2] n with no significant solvent effect of water. It has been confirmed that this polymerization reaction leads spontaneously to a planar cluster, which is regarded as a part of the brucite layer, The results suggest that the layered structure of brucite is a natural consequence of polymerization. These findings will be utilized to establish microscopic modeling for studying a templating effect on the formation of an inorganic thin film..
77. Haruyuki Nakano, Kimihiko Hirao, Recent advances in multireference-based perturbation theory, Bulletin of the Korean Chemical Society, 10.5012/bkcs.2003.24.6.812, 24, 6, 812-816, 2003.06, Accurate ab initio computational chemistry has evolved dramatically. In particular, the development of multireference-based approaches has opened up a completely new area, and has had a profound impact on the potential of theoretical chemistry. Multireference-based perturbation theory (MRPT) is an extension of the closed-shell single reference Møller-Plesset method, and has been successfully applied to many chemical and spectroscopic problems. MRPT has established itself as an efficient technique for treating nondynamical and dynamical correlations. Usually, a complete active space self-consistent field (CASSCF) wave function is chosen as a reference function of MRPT. However, CASSCF often generates too many configurations, and the size of the active space can outgrow the capacity of the present technology. Many attempts have been proposed to reduce the dimension of CASSCF and to widen the range of applications of MRPT. This review focuses on our recent development in MRPT..
78. Henryk A. Witek, Haruyuki Nakano, Kimihiko Hirao, Multireference perturbation theory with optimized partitioning. I. Theoretical and computational aspects, Journal of Chemical Physics, 10.1063/1.1563618, 118, 18, 8197-8206, 2003.05, A multireference perturbation method that is based on Rayleigh-Schrodinger perturbation theory and uses an optimized partitioning is presented. The method is abbreviated as MROPT. The optimization of the zeroth-order energies for the nth-order MROPT method is performed by putting a condition Ψ(n)=0 on the first neglected term in the perturbative expansion of the wave function. This allows for cancellation of a large part of errors arising from truncating the wave function. Explicit equations that enable determining the optimized zeroth-order energies for the second-, third-, and fourt-order perturbation theory are given..
79. T. Yanai, H. Nakano, T. Nakajima, T. Tsuneda, S. Hirata, Y. Kawashima, Y. Nakao, M. Kamiya, H. Sekino, and K. Hirao, UTChem - A Program for ab initio Quantum Chemistry, Proceedings of Computational Science - ICCS 2003, Lecture Notes in Computer Science, Vol. 2660, edited by P. M. A. Sloot, D. Abramson, A. Bogdanov, J. J. Dongarra, A. Zomaya, and Y. Gorbachev (Springer-Verlag, Berlin, 2003), pp. 84-95, 2003.01.
80. Haruyuki Nakano, Ryuma Uchiyama, Kimihiko Hirao, Quasi-degenerate perturbation theory with general multiconfiguration self-consistent field reference functions, Journal of Computational Chemistry, 10.1002/jcc.10050, 23, 12, 1166-1175, 2002.09, The quasi-degenerate perturbation theory (QDPT) with complete active space (CAS) self-consistent field (SCF) reference functions is extended to the general multiconfiguration (MC) SCF references functions case. A computational scheme that utilizes both diagrammatic and sum-over-states approaches is presented. The second-order effective Hamiltonian is computed for the external intermediate configurations (including virtual or/and core orbitals) by the diagrammatic approach and for internal intermediate configurations (including only active orbitals) by the configuration interaction matrix-based sum-over-states approach. The method is tested on the calculations of excitation energies of H2O, potential energy curves of LiF, and valence excitation energies of H2CO. The results show that the present method yields very close results to the corresponding CAS-SCF reference QDPT results and the available experimental values. The deviations from CAS-SCF reference QDPT values are less than 0.1 eV on the average for the excitation energies of H2O and less than 1 kcal/mol for the potential energy curves of LiF. In the calculation of the valence excited energies of H2CO, the maximum deviation from available experimental values is 0.28 eV..
81. T. Nakajima, T. Tsuneda, H. Nakano, and K. Hirao, Recent Advances in Electronic Structure Theory, J. Theor. Comput. Chem., 1, 109-136 (2002), 2002.01.
82. Haruyuki Nakano, Kazushi Sorakubo, Kenichi Nakayama, Kimihiko Hirao, Complete active space valence bond (CASVB) method and its application to chemical reactions, Theoretical and Computational Chemistry, 10, 55-77, 2002.01, The complete active space valence bond (CASVB) method is an approach for interpreting complete active space self-consistent field (CASSCF) wave functions by means of valence bond resonance structures built on atom-like localized orbitals. The transformation from CASSCF to CASVB wave functions does not change the variational space, and thus it is done without loss of information on the total energy and wave function. In the present article, some applications of the CASVB method to chemical reactions are reviewed following a brief introduction to this method: unimolecular dissociation reaction of formaldehyde, H2CO → H2+CO, and hydrogen exchange reactions, H2+X → H+HX (X=F, Cl, Br, and I)..
83. Y. Matano, H. Nomura, H. Suzuki, M. Shiro, H. Nakano, Synthesis, structure, and reactions of (acylimino)triaryl-λ5-bismuthanes
First comparative study of the (acylimino)pnictorane series, Journal of the American Chemical Society, 10.1021/ja003623l, 123, 44, 10954-10965, 2001.11, The synthesis, structure, and reactions of (acylimino)triaryl-λ5-bismuthanes and a comparative study of the structure and reactivity of a series of (acylimino)pnictoranes are reported. Treatment of ortho-substituted triarylbismuth dichlorides 1 (Ar3BiCl2; Ar = 2-MeC6H4, 2-MeOC6H4, 2,4,6-Me3C6H2) with amides 2 (H2-NCOR; R = CF3, CCl3, 3,5-(CF3)2C6H3) in the presence of 2.2 equiv of KO-t-Bu in dichloromethane afforded (acylimino)triaryl-λ5-bismuthanes 3 (Ar3Bi=NCOR) in yields of 77-96%. The ortho-substituted aryl ligands and the electron-withdrawing N-substituents afford kinetic and thermodynamic stabilization, respectively, to the reactive Bi=N bond. The structures and properties of a series of (acylimino)pnictoranes (Ar3M=NCOR and H3M=NCOCF3; M = P, As, Sb, Bi) are compared by IR and 13C and 15N NMR, X-ray crystallography, and ab initio molecular orbital calculations. It was found that the contribution of the M+-N=C-O- canonical form becomes more prominent and the single-bond character of the M=N bond increases progressively as the pnictogen atom becomes heavier. The Bi=N bond of (acylimino)-λ5-bismuthanes 3 possesses a highly polarized single-bond character, probably due to the differences in orbital size and electronegativity between the bismuth and nitrogen atoms. Thermal decomposition of (aroylimino)triaryl-λ5-bismuthane 3f (o-Tol3Bi=NCOAr; Ar = 3,5-(CF3)2C6H3) produces a gel in dry conditions or aniline 12 (ArNH2) in slightly wet conditions with a good recovery of tris(2-methylphenyl)bismuthane (4a). It is likely that the aryl isocyanate 13 (ArNCO) is produced during the thermolysis via a concerted C → N migration of the Ar group with an elimination of the triarylbismuthonio group as bismuthane 4a. (Acylimino)triaryl-λ5-bismuthanes 3 oxidize 1,1,2,2-tetraphenylethanediol, benzenethiol, methanol, and ethanol to benzophenone, diphenyl disulfide, methyl formate, and acetaldehyde, respectively, in two different reaction pathways depending on the structure of the substrates. Compound 3d (o-Tol3Bi=NCOCCl3) transfers the nitrenoid moiety to triphenylphosphane, triphenylarsane, and tris(2-methylphenyl)stibane to give the corresponding (acylimino)pnictoranes (Ar3M=NCOCl3; M = P, As, Sb) and 4a, suggesting that 3d is thermodynamically much less stable than their lighter pnictogen counterparts. The copper-catalyzed decomposition of 3 (o-Tol3Bi=NCOR) afforded N-acyl-o-toluidines 18 (o-TolNHCOR) via a Bi → N migration of the tolyl group. The observed reactivities of (acylimino)triaryl-λ5-bismuthanes 3 demonstrate a good leaving ability of the bismuthonio group..
84. Haruyuki Nakano, Takahito Nakajima, Takao Tsuneda, Kimihiko Hirao, Research activities of the theoretical chemistry group at the University of Tokyo, Journal of Molecular Structure: THEOCHEM, 10.1016/S0166-1280(01)00546-2, 573, 1-3, 91-128, 2001.10, One of the authors (Kimihiko Hirao) was invited to the University of Tokyo in 1993 as the first professor of theoretical chemistry. Since then, our quantum chemistry research group has grown larger and larger and has now become one of the centers of theoretical chemistry in Japan. We are aiming at developing accurate molecular theory on systems containing hundreds of atoms. We continue our research in the following three directions: (i) development of new ab initio theory, particularly multireference-based perturbation theory; (ii) development of molecular theory including relativistic effects; and (iii) development of exchange and correlation functionals in density functional theory. We have enjoyed good progress in each of the above areas. We are very excited about our discoveries of new theory and new algorithms and we would like to share this enthusiasm with readers. The present review is a summary of our research activities achieved in the last 5 years..
85. Yuka Kobayashi, Haruyuki Nakano, Kimihiko Hirao, Multireference Møller-Plesset perturbation theory using spin-dependent orbital energies, Chemical Physics Letters, 10.1016/S0009-2614(01)00140-3, 336, 5-6, 529-535, 2001.03, The use of spin-dependent orbital energies is proposed in the multireference Møller-Plesset perturbation theory. In this method a single canonical Fock orbital set is used for both alpha and beta electrons, while the orbital energies depend on the spin of the electron that occupies the orbital. The method is tested on the energy splitting between states of different spins in the CH2, CF2, CO, O2, N2+, and o-benzyne molecules. The results agree well with available experimental data; the deviations are within 4 kcal/mol in all cases considered..
86. Kou Takeda, Takashi Tsuchiya, Haruyuki Nakano, Tetsuya Taketsugu, Kimihiko Hirao, Stability of multiply charged anions of lanthanide hexafluorides LnF6/2- and LnF6/3- (Ln = Ce to Lu), Journal of Molecular Structure: THEOCHEM, 10.1016/S0166-1280(00)00667-9, 537, 1, 107-115, 2001.03, The kinetic and electronic stability of a series of free LnF6/9--type lanthanide hexafluorides (Ln = Ce to Lu; q = 2, 3) is studied with the relativistic effective core potentials of Cundari and Stevens. In all complexes (LnF6/2- and LnF6/3-), the octahedral or almost octahedral structure is calculated to be stable through normal mode analyses at the unrestricted Hartree-Fock (UHF) and complete active space self-consistent field (CASSCF) levels. The electronic stability of all complexes is investigated using the state-averaged CASSCF and quasidegenerate perturbation theory with multiconfigurational self-consistent field reference functions (MC-QDPT) schemes. The most electronically stable LnF6/9- is LnF6/2- for Ce, Pr, Nd, Pm, Sm, Tb, Dy, Ho, Er, Tm, Yb. These LnF6/2- anions are found to have an energy barrier with respect to the unimolecular decomposition LnF6/2- → LnF6/5- + F- and are predicted to be long-lived species formally existing in a meta-stable state..
87. Haruyuki Nakano, Junji Nakatani, Kimihiko Hirao, Second-order quasi-degenerate perturbation theory with quasi-complete active space self-consistent field reference functions, Journal of Chemical Physics, 10.1063/1.1332992, 114, 3, 1133-1141, 2001.01, Based on quasi complete active space self-consistent field (QCAS-SCF) reference functions, a quasi-degenerate perturbation theory (QDPT) was presented. Using a diagrammatic approach, a computational scheme to second-order was described. Second-order effective Hamiltonian consisted of the contribution from external excitation which involved core/or/and virtual orbitals, and internal excitations, which involved only active orbitals..
88. Yoong Kee Choe, James P. Finley, Haruyuki Nakano, Kimihiko Hirao, On the performance of diagrammatic complete active space perturbation theory, Journal of Chemical Physics, 10.1063/1.1316044, 113, 18, 7773-7778, 2000.11, The accuracy of the second-order diagrammatic complete active space perturbation was analyzed for the excited states of C2, H2O, CO and formamide. The study also probed the differences of the system with the ab initio and full configuration interaction (FCI) techniques along with the relative excitation energies..
89. Haruyuki Nakano, Kimihiko Hirao, A quasi-complete active space self-consistent field method, Chemical Physics Letters, 10.1016/S0009-2614(99)01364-0, 317, 1-2, 90-96, 2000.01, A multi-configuration self-consistent field method is proposed in which a quasi-complete active space, which is the product space of complete active spaces, is used as a variational space. The computational effort for wavefunctions is significantly reduced compared with the complete active space self-consistent field (CAS-SCF) method. Efficient formulae with segmented alpha and beta strings are derived. The scheme is tested on the spectroscopic constants and a potential energy curve of CO, the transition state barrier height of the reaction, H2CO→H2+CO, and the energy difference between trans- and cis-butadiene. The results are in good agreement with the corresponding CAS-SCF results..
90. Takeshi Yanai, Kazuhiro Ishida, Haruyuki Nakano, Kimihiko Hirao, New Algorithm for Electron Repulsion Integrals Oriented to the General Contraction Scheme, International Journal of Quantum Chemistry, 10.1002/(SICI)1097-461X(2000)76:3<396::AID-QUA8>3.0.CO;2-A, 76, 3, 396-406, 2000.01, An algorithm for computing electron repulsion integrals (ERIs) oriented to the general contraction scheme is presented. The accompanying coordinate expansion (ACE) method of Ishida is utilized to derive an efficient algorithm. The performance estimated with the floating-point operation (FLOP) count is about N2 times and more as efficient as the conventional algorithm for the segmented contraction scheme, where N indicates the number of contracted Gaussian-type orbitals (GTOs) contained in a set of generally contracted GTOs. The efficiency is also confirmed by using a realistic molecular system, the benzene molecule, with C:14s9p/3s2p, H:8s4p/2s1p, and C:14s9p/6s5p, H:8s4p/4s3p basis sets. The measured central processing unit (CPU) time is in good agreement with the FLOP count estimation..
91. Yukio Kawashima, Tomohiro Hashimoto, Haruyuki Nakano, Kimihiko Hirao, Theoretical study of the valence π → π* excited states of polyacenes
Anthracene and naphthacene, Theoretical Chemistry Accounts, 10.1007/s002140050472, 102, 1-6, 49-64, 1999.06, The valence π → π* excited states of anthracene and naphthacene are studied with multireference perturbation theory with complete active space self-consistent field reference functions. The predicted spectra provide a consistent assignment of all one-and two-photon spectra and T-T spectra of low-lying valence π → π* excited states of anthracene and naphthacene. The present theory predicts the valence π → π* excitation energies with an accuracy of 0.15 eV for anthracene and of 0.25 eV or better for naphthacene. The excited states of anthracene and naphthacene are compared with those of benzene and naphthalene studied previously. The present calculations predict that, going from anthracene to naphthacene, there is a symmetry reversal of the two lowest singlet state transitions, but not for the triplet, just as indicated by the experimental data. Some general trends of polyacene excited states are discussed based on the calculated results for benzene to naphthacene. Conclusive results obtained for anthracene and naphthacene can be used as a model for understanding the excited states of larger polyacenes..
92. Haruyuki Nakano, Kenichi Nakayama, Kimihiko Hirao, Complete active space valence bond method applied to chemical reactions, Journal of Molecular Structure: THEOCHEM, 10.1016/S0166-1280(98)00462-X, 461-462, 55-69, 1999.04, A complete active space valence bond (CASVB) method with orthogonal and non-orthogonal orbitals is applied to the collinear exchange reaction H + H2 → H2 + H and the unimolecular dissociation H2CO → H2 + CO. The bond nature during the reactions is analyzed using the occupation number (weight) of the valence bond resonance structures. The CASVB descriptions with orthogonal and non-orthogonal orbitals give a similar picture, although the ratio of covalent vs. ionic bonds are quite different. In the H2CO → H2 + CO reaction, the CH bond dissociation and HH bond formation occur after passing through the transition state. CASVB gives a clear understanding of reaction mechanisms in terms of competing bonding schemes whose weights change along the intrinsic reaction coordinate..
93. Takashi Tsuchiya, Tetsuya Taketsugu, Haruyuki Nakano, Kimihiko Hirao, Theoretical study of electronic and geometric structures of a series of lanthanide trihalides LnX3 (Ln = La-Lu; X = Cl, F), Journal of Molecular Structure: THEOCHEM, 10.1016/S0166-1280(98)00461-8, 461-462, 203-222, 1999.04, Ab initio molecular orbital calculations are performed for a series of lanthanide trihalides LnX3 (Ln = La to Lu; X = Cl, F), with the relativistic effective core potentials of Cundari and Stevens, to characterize the tendency in their electronic and geometric structures. In all the complexes (LnX3), the planar structure (D(3h) symmetry) is calculated to be stable through normal mode analyses at the complete active space self-consistent field (CASSCF) levels. In the LnX3, the number of 4f-electrons increases with increasing the atomic number, and 1.2-1.6 (2.1-2.2) electrons are transferred from Ln to Cl (F); the Ln-X bonds are dominated by charge- transfer but have a significant amount of covalent character that involves the 5d-orbital on Ln. It is also found that, along the lanthanide trihalide series, the first seven f-electrons occupy 4f-orbitals one by one from the lowest one up, while the second seven occupy 4f-orbitals from the highest one down, at the Hartree-Fock level. This occupation mechanism is explained in terms of the self-repulsion interactions between two electrons occupying the same spatial 4f-orbital. The Ln-X bond lengths, net charges, and vibrational frequencies show monotonic variation along the lanthanide series, which corresponds to the lanthanide contraction. State-averaged CASSCF calculations are also carried out for LnCl3, in a combination with spin-orbit calculations using the atomic spin-orbit coupling constant for the f- electrons, to investigate the energy splitting of the nearly-degenerate low- lying states in the scheme of L-S coupling..
94. Kurt R. Glaesemann, Mark S. Gordon, Haruyuki Nakano, A study of FeCO+ with correlated wavefunctions, Physical Chemistry Chemical Physics, 10.1039/a808518h, 1, 6, 967-975, 1999.03, A study of FeCO+ and Fe+ using both the second-order multi- configurational quasi-degenerate perturbation theory (MC-QDPT2) method and the coupled cluster theory with single and double replacements (augmented by perturbative triples) [CCSD(T)] method are presented. An all-electron triple- ζ valence plus polarization basis set was used in all calculations. The equilibrium CCSD(T) geometry of FeCO+ is found to be linear (4Σ-) with a Fe+ to CO distance of 1.905 Å and a CO bond distance of 1.133 Å. The dissociation energy D(0) of 4Σ- FeCO(+) to 6D Fe+ and 1Σ+ CO is predicted to be 28.8 kcal mol-1, which is within the experimental range. Excited state properties including potential energy surfaces and De are predicted for the low lying sextet and quartet states of FeCO+. The first excited state is predicted to be hA with a D(e) of 17.6 kcal mol-1. The lowest sextet state is predicted to be 6Δ with a D(0) of 12.3 kcal mol- 1. Several examples of pathological behavior at many levels of theory have been discovered and are discussed..
95. Yasuyuki Tsurutani, Shinjiro MacHida, Kazuyuki Horie, Kawashima Yukio Kawashima, Haruyuki Nakano, Kimihiko Hirao, Fluorescence and photoinversion reactions in solutions of chiral diaryl sulfoxides with various sizes of aromatic rings, Journal of Photochemistry and Photobiology A: Chemistry, 10.1016/S1010-6030(99)00010-6, 122, 3, 161-168, 1999.03, Chiral aryl 4-tolyl sulfoxides substituted with several sizes of aromatic rings, (S)-(-)-phenyl 4-tolyl sulfoxide (PHSO), (R)-(+)-1-naphthyl 4-tolyl sulfoxide (NASO), (R)-(+)-9-phenanthryl 4-tolyl sulfoxide (PNSO), and (R)-(+)-1-pyrenyl 4-tolyl sulfoxide (PYSO), were prepared. It has turned out for the first time that there are n-σ*, π-σ* and π-π* states in excited states of these molecules by MO calculation. Fluorescence spectra and quantum yields of fluorescence, Φfl, were measured in polar and non-polar solvents. Quantum yields of photoinversion, Φinv, and photolysis, Φdec, were also obtained with CD and HPLC measurements. Aromatic-ketone like characteristics have been noticed in the fluorescence measurements, i.e., fluorescence has been observed from sulfoxides substituted with large aromatic rings and their fluorescence becomes strong in a polar solvent. We attributed these characteristics to the decrease in π-π* transition energy as the degree of conjugation increases, while n-σ* and π-σ* transition energy does not decrease so much. The values of Φinv and Φdec for PHSO, NASO and PNSO were found to be 0.3-0.4 (Φinv) and 0.03-0.05 (Φdec). The quantum yields for PYSO were measured as Φinv = 0.02-0.03 in methanol and hexane, and Φdec = 0.002-0.003 in methanol and 0.012-0.016 in hexane. It was found that quantum yields of photoinversion and photolysis decrease as the π-π* transition energy decreases. We concluded that photoinversion occur during change in electronic states from n-σ* states to the ground state..
96. T. Hashimoto, Y.-K. Choe, H. Nakano, and K. Hirao, Theoretical study of the Q and B bands of free-base, magnesium, and zinc porphyrins, and their derivatives, J. Phys. Chem. A, 103, 1894-1904 (1999), 1999.01.
97. T. Tsuchiya, T. Taketsugu, H. Nakano, and K. Hirao, Theoretical study of electronic and geometric structures of a series of lanthanide trihalaides LnX3 (Ln = La-Lu; X = Cl, F), J. Mol. Struct. (Theochem), 461-462 (Morokuma Special Issue), 203-222 (1999), 1999.01.
98. Yoong Kee Choe, Tomohiro Hashimoto, Haruyuki Nakano, Kimihiko Hirao, Theoretical study of the electronic ground state of iron(II) porphine, Chemical Physics Letters, 10.1016/S0009-2614(98)00986-5, 295, 4, 380-388, 1998.10, Ten low-lying electronic states of Fe(II)-porphine, the 5A1g, 5Eg, 5B2g, 3A2g, 3B2g, 3Eg(A), 3Eg(B), 1A1g, 1B2g and 1Eg states, are studied with multireference Møller-Plesset perturbation theory with complete active space self-consistent field (CASSCF) reference functions. Triplet and singlet states are significantly multiconfigurational in character. The ten low-lying states are computed to be within a 2 eV span and the 5A1g state is predicted to be the lowest. At the CASSCF level, all the quintet states are lower in energy than the triplets. This tendency is reversed, except for the 5A1g state, after perturbation theory is applied. Among controversial candidates for the triplet ground state, the 3Eg state is computed to be more stable, by 0.18~0.23 eV, than the 3A2g and 3B2g states..
99. Tomohiro Hashimoto, Haruyuki Nakano, Kimihiko Hirao, Theoretical study of valence and Rydberg excited states of benzene revisited, Journal of Molecular Structure: THEOCHEM, 10.1016/S0166-1280(98)00156-0, 451, 1-2, 25-33, 1998.09, The multireference Møller-Plesset perturbation (MRMP) theory with complete active space self-consistent field (CASSCF) reference functions is applied to the study of the singlet and triplet valence π-π* excited states and Rydberg excited states of benzene in the ultraviolet region. The overall accuracy of MRMP is surprisingly high. The average deviations of the excitation energies from the available experimental values are 0.1 eV for the valence excited states and 0.15 eV for the Rydberg states. A comparison is made with recent results of single reference-based methods. It is concluded that MRMP is able to describe satisfactorily excited states with a double excitation character, while single reference-based methods are not..
100. Haruyuki Nakano, Kimihiko Hirao, Mark S. Gordon, Analytic energy gradients for multiconfigurational self-consistent field second-order quasidegenerate perturbation theory (MC-QDPT), Journal of Chemical Physics, 10.1063/1.475975, 108, 14, 5660-5669, 1998.04, An analytic energy gradient method for second-order quasidegenerate perturbation theory with multiconfigurational self-consistent field reference functions (MC-QDPT) is derived along the lines of the response function formalism (RFF). According to the RFF, the gradients are calculated without solving coupled perturbed equations. Instead, it is necessary to solve seven sets of linear equations in order to determine Lagrangian multipliers, corresponding to four sets of parameter constraining conditions and three sets of additional parameter defining conditions in the Lagrangian. Just one of these linear equations is a large scale linear equation; the others are reducible to just partial differentiations or simple equations solvable by straightforward subroutines..
101. Y.-K. Choe, T. Hashimoto, H. Nakano, and K. Hirao, Theoretical study of the electronic ground state of Iron (II) porphine, Chem. Phys. Lett., 295, 380-388 (1998), 1998.01.
102. Kenichi Nakayama, Haruyuki Nakano, Kimihiko Hirao, Theoretical study of the π → π* excited states of linear polyenes
The energy gap between 11Bu+ and 21Ag- states and their character, International Journal of Quantum Chemistry, 10.1002/(SICI)1097-461X(1998)66:2<157::AID-QUA7>3.0.CO;2-U, 66, 2, 157-175, 1998.01, Multireference perturbation theory with complete active space self-consistent field (CASSCF) reference functions is applied to the study of the valence π → π* excited states of 1,3-butadiene, 1,3,5-hexatriene, 1,3,5,7-octatetraene, and 1,3,5,7,9-decapentaene. Our focus was put on determining the nature of the two lowest-lying singlet excited states, 11Bu+ and 21Ag-, and their ordering. The 11Bu+ state is a singly excited state with an ionic nature originating from the HOMO → LUMO one-electron transition while the covalent 21Ag- state is the doubly excited state which comes mainly from the (HOMO)2 → (LUMO)2 transition. The active-space and basis-set effects are taken into account to estimate the excitation energies of larger polyenes. For butadiene, the 11Bu+ state is calculated to be slightly lower by 0.1 eV than the doubly excited 21Ag- state at the ground-state equilibrium geometry. For hexatriene, our calculations predict the two states to be virtually degenerate. Octatetraene is the first polyene for which we predict that the 21Ag- state is the lowest excited singlet state at the ground-state geometry. The present theory also indicates that the 21AG- state lies clearly below the 11Bu+ state in decapentaene with the energy gap of 0.4 eV. The 0-0 transition and the emission energies are also calculated using the planar C2h relaxed excited-state geometries. The covalent 21Ag- state is much more sensitive to the geometry variation than is the ionic 11Bu+ state, which places the 21Ag- state significantly below the 11Bu+ state at the relaxed geometry..
103. Kimihiko Hirao, Haruyuki Nakano, Kenichi Nakayama, A complete active space valence bond method with nonorthogonal orbitale, Journal of Chemical Physics, 10.1063/1.475300, 107, 23, 9966-9974, 1997.12, A complete active space self-consistent field (SCF) wave function is transformed into a valence bond type representation built from nonorthogonal orbitals, each strongly localized on a single atom. Nonorthogonal complete active space SCF orbitals are constructed by Ruedenberg's projected localization procedure so that they have maximal overlaps with the corresponding minimum basis set of atomic orbitals of the free-atoms. The valence bond structures which are composed of such nonorthogonal quasiatomic orbitals constitute the wave function closest to the concept of the oldest and most simple valence bond method. The method is applied to benzene, butadiene, hydrogen, and methane molecules and compared to the previously proposed complete active space valence bond approach with orthogonal orbitals. The results demonstrate the validity of the method as a powerful tool for describing the electronic structure of various molecules..
104. Yukio Kawashima, Kenichi Nakayama, Haruyuki Nakano, Kimihiko Hirao, Theoretical study of the π → π * excited states of linear polyene radical cations and dications, Chemical Physics Letters, 10.1016/S0009-2614(97)00084-5, 267, 1-2, 82-90, 1997.03, Multireference Møller-Plesset theory is applied to the study of the valence π → π * excited states of radical cations and dications of butadiene, hexatriene, octatetraene and decapentaene. The present theory satisfactorily describes the low-lying excited states of cations within an error of 0.1 eV. Theory confirms the general tendency observed in carotenoids that the first transition of the dications of polyenes is at a higher energy than the intense transition of the radical cations and at a lower energy than the first allowed transition of the neutral species..
105. Haruyuki Nakano, Kenichi Nakayama, Kimihiko Hirao, Michel Dupuis, Transition state barrier height for the reaction H2CO→H2+CO studied by multireference Møller-Plesset perturbation theory, Journal of Chemical Physics, 106, 12, 4912-4917, 1997.02, The second-order multireference Møller-Plesset perturbation method (MRMP) was applied to the accurate estimation of the transition state barrier height of H2CO→H2+CO reaction. The best estimate for the classical barrier height is 84.5 kcal/mol at the highest level of MRMP theory with the quadruple zeta plus triple polarization basis set and with the active space of 12 electrons in 11 active orbitals. The inclusion of zero-point vibrational energy correction reduces the activation energy to 79.1 kcal/mol, which is in excellent agreement with the experimental value of 79.2±0.8 kcal/mol [Polik, Guyer, and Moore, J. Chem. Phys. 92, 3453 (1990)]. Analysis of the second-order energies in terms of internal, semi-internal, and external contributions shows that the present MRMP provides a well balanced treatment for the estimation of the energy difference between the equilibrium and transition state structures..
106. Mark S. Gordon, Thomas J. Barton, Haruyuki Nakano, Ring opening of silacyclobutane, Journal of the American Chemical Society, 10.1021/ja9715354, 119, 49, 11966-11973, 1997.01, Multiconfigurational self-consistent field (MCSF) wave functions, augmented by second order perturbation theory to partially recover the dynamic correlation, suggests that the most likely route from silacyclobutane to products ethylene + silene is initial cleavage of a ring CC bond to form a trans ·CH2SiH2CH2CH2· diradical, followed by rupture of the central SiC bond. This prediction is in agreement with the available experimental results. While this trans diradical is predicted to be a minimum on the MCSF ground state potential energy surface, the transition state separating this species from products disappears when dynamic correlation is added. Therefore, the bottleneck on this part of the potential energy surface is likely to be the transition state for the initial CC bond cleavage. The alternative mechanism that is initiated by cleavage of a ring SiC bond leads to an analogous trans ·SiH2CH2CH2CH2· diradical. The transition state leading to this species in the highest point on this minimum energy path and is nearly 6 kcal/mol higher in energy than the transition state that leads to the ·CH2SiH2CH2CH2· diradical. A transition state for the concerted decomposition has also been found, but this structure is much higher in energy (~10 kcal/mol) than the highest point on the preferred route. Comparison of the multireference perturbation theory and coupled cluster CCSD(T) results suggests that production of propylsilylene should be both thermodynamically and kinetically competitive with the formation of ethylene+silene. This is consistent with the mechanism proposed by one of us in 1984..
107. Kimihiko Hirao, Haruyuki Nakano, Kenichi Nakayama, Michel Dupuis, A complete active space valence bond (CASVB) method, Journal of Chemical Physics, 10.1063/1.472754, 105, 20, 9227-9239, 1996.01, A complete active space valence bond (CASVB) method is proposed which is particularly adapted to chemical interpretation. A CASVB wave function can be obtained simply by transforming a canonical CASSCF function and readily interpreted in terms of the well known classical VB resonance structures. The method is applied to the ground and excited states of benzene, butadiene, and the ground state of methane. The CASVB affords a clear view of the wave functions for the various states. The electronic excitation is represented in a VB picture as rearrangements of the spin couplings or as charge transfers which involve breaking covalent bonds and forming new ionic bonds. The former gives rise to covalent excited states and the latter to ionic excited states. The physical reasons why it is so difficult to describe the ionic excited states at the CASSCF level with a single active space and why the lowest 1 1B2+ state in cis-butadiene is so stabilized compared to the corresponding 1 1Bu+ state in the trans isomer are easily identified in view of a VB picture. The CASVB forms a useful bridge from molecular orbital theory to the familiar concepts of chemists..
108. Haruyuki Nakano, Takao Tsuneda, Tomohiro Hashimoto, Kimihiko Hirao, Theoretical study of the excitation spectra of five-membered ring compounds
Cyclopentadiene, furan, and pyrrole, Journal of Chemical Physics, 10.1063/1.470926, 104, 6, 2312-2320, 1996.01, Multireference perturbation theory with complete active space self-consistent field (CASSCF) reference functions was applied to the study of the valence and Rydberg excited states in the range of 5-8 eV of five-membered ring compounds, cyclopentadiene, furan, and pyrrole. The spectra of these molecules have been studied extensively for many years but characterization is far from complete. The present approach can describe all kinds of excited states with the same accuracy. The calculated transition energies are in good agreement with corresponding experimental data. We were able to predict the valence and Rydberg excited states with an accuracy of 0.27 eV or better except for the B2+ of pyrrole. The valence excited states of five-membered ring compounds were interpreted in terms of the covalent minus states and ionic plus states of the alternate symmetry. The unobserved 1A]1→A1- transition with very weak intensity, which is hidden under the strong 1A1→B2+ transition, is also discussed. Overall, the present theory supports the assignments recently made by Serrano-Andres et al. based on the CASSCF plus second-order perturbation results. However, there remain some discrepancies in the assignment of the spectrum of pyrrole..
109. Haruyuki Nakano, Tohru Nakajima, Shigeru Obara, Efficient and stable method of searching for optimum structures of molecules containing cyclic parts, Chemical Physics Letters, 10.1016/0009-2614(91)85083-9, 177, 4-5, 458-462, 1991.03, An efficient and stable method of searching for optimum structures of molecules containing cyclic parts is proposed, where both the Cartesian and the internal coordinates are improved independently at each iteration of the optimization, and are used for the next geometry of the cyclic parts and of the remaining parts, respectively. The utilization of the Cartesian coordinates at the cyclic parts allows us to avoid the disastrous and irrecoverable distortions, which frequently occur if one uses the internal coordinates. For the remaining parts, the internal coordinates are used, so that an efficient calculation is obtained. The present method is tested in the search for the geometries of pyridine and ethylene oxide in the ground state and compared with the usual methods which employ either the internal coordinates or the Cartesian coordinates as optimization variables; our new method is found to be more efficient and more stable than the usual methods..
110. T. Hashimoto, H. Nakano, K. Hirao, Theoretical study of the valence π→π* excited states of polyacenes
Benzene and naphthalene, Journal of Chemical Physics, 10.1063/1.471286, 104, 16, 6244-6258, 1996.01, Multireference perturbation theory with complete active space self-consistent field (CASSCF) reference functions was applied to the study of the valence π→πexcited states of benzene and naphthalene. The eigenvectors and eigenvalues of CASSCF with valence π active orbitals satisfy pairing properties for the alternant hydrocarbons to a good approximation. The excited states of polyacenes are classified into the covalent minus states and ionic plus states with the use of the alternancy symmetry. The present theory satisfactorily describes the ordering of low-lying valence π→πexcited states. The overall accuracy of the present approach is surprisingly high. We were able to predict the valence excitation energies with an accuracy of 0.27 eV for singlet u states and of 0.52 eV or better for singlet g states of naphthalene. Our predicted triplet states spectrum provides a consistent assignment of the triplet-triplet absorption spectrum of naphthalene. For benzene we were able to predict the valence excitation energy with an accuracy of about 0.29 eV. The covalent minus states and ionic plus states exhibit different behavior as far as the electron correlation is concerned. The ionic plus states are dominated by the single excitations but covalent minus states include a large fraction of doubly excited configurations. The covalent minus states always give lower energy than the corresponding ionic plus states. This is true for triplet states. The dynamic σ-π polarization effects introduced by perturbation theory are significant for the ionic plus states while those on covalent excited states are usually of the same order as in the covalent ground state. The enlargement of the active space of the reference functions represents a great improvement of the description of the ionic states. The present approach with the pairing properties has proved to be of great value in understanding and predicting the experimental data of the alternant hydrocarbons..
111. K. Hirao, H. Nakano, T. Hashimoto, Multireference Møller-Plesset perturbation treatment for valence and Rydberg excited states of benzene, Chemical Physics Letters, 10.1016/0009-2614(95)00160-6, 235, 5-6, 430-435, 1995.03, State-specific multireference Møller-Plesset perturbation theory has been applied to the study of valence and Rydberg excitation energies of benzene. The results compare well with experiment. The calculated valence π-π* excitation energies (experimental values in parentheses) are 1B2u, 4.77 (4.90), 1B1u, 6.98 (6.20), 1E1u, 6.98 (6.94) and 1E2g, 7.88 (7.80) eV. Results of similar accuracy are obtained for the valence triplet excited states. The Rydberg excitation energies are also predicted with an accuracy of 0.18 eV or better..
112. T. Tsuneda, H. Nakano, K. Hirao, Study of low-lying electronic states of ozone by multireference Møller-Plesset perturbation method, The Journal of Chemical Physics, 10.1063/1.470378, 103, 15, 6520-6528, 1995.01, The geometry and relative energy of the seven low-lying electronic states of ozone and the ground state of ozonide anion have been determined in C 2v symmetry by the complete active space self-consistent field (CASSCF) and the multireference Møller-Plesset perturbation (MRMP) methods. The results are compared with the photodetachment spectra of O 3- observed recently by Arnold et al. The theoretical electron affinity of ozone is 1.965 eV, which is 0.14 eV below the experimental result of 2.103 eV. The calculated adiabatic excitation energies (assignment of Arnold et al. in parentheses) of ozone are 3A2 0.90 eV (1.18 eV), 3B2, 1.19 eV (1.30 eV), 3B 1, 1.18 eV (1.45 eV), 1A2, 1.15 eV (∼1.6 eV), 1B1, 1.65 eV (2.05 eV), and 1B 2, 3.77 eV (3.41 eV), respectively. Overall the present theory supports the assignment of Arnold et al. However, the simple considerations of geometry and energy are insufficient to determine a specific assignment of the 3B2 and 3B1 states. The dissociation energy of the ground state of ozone is computed to be 0.834 eV at the present level of theory. The present theory also predicts that none of the excited states lies below the ground state dissociation limit of O3..
113. Haruyuki Nakano, Shigeru Obara, Convergence property of multireference many-body perturbation theory analyzed by the use of a norm of effective Hamiltonian, Theoretica Chimica Acta, 10.1007/BF01122429, 86, 5, 369-377, 1993.10, It is proposed to use a norm of a nth order effective Hamiltonian, for analyzing the convergence property of the multireference many-body perturbation theory (MR-MBPT). The utilization of the norm allows us to employ only (1) a single number for all the states that we are interested in, and (2) values which decreases from the positive side to zero as the order n of the perturbation increases. This characteristic features are in contrast to those in the usually used scheme where several numbers, namely, the eigenvalues of the target states, should be used and they may oscillate around exact eigenvalues. The present method has been applied to MR-MBPT calculations of the (H2)2, CH2, and LiH molecules based on the multireference versions of Rayleigh-Schrödinger PT, Kirtman-Certain-Hirschfelder PT, and the canonical Van Vleck PT; and following features are found: (1) the above three versions of the perturbation theories have essentially the same convergence property judged from the lowering of the norm; (2) the lower order truncation of the perturbation series gives reasonable solutions; (3) the norm decreases irrespective of the perturbation expansion being convergent or divergent for the first several orders (up to about the sixth order)..
114. Haruyuki Nakano, MCSCF reference quasidegenerate perturbation theory with Epstein-Nesbet partitioning, Chemical Physics Letters, 10.1016/0009-2614(93)89016-B, 207, 4-6, 372-378, 1993.05, A quasidegenerate perturbation theory (QDPT) with Epstein-Nesbet partitioning based on MCSCF reference functions is presented. The formulas for CSF-based matrix operations are derived. They are applied to the systems BeH2 and CO, and compared with other methods. The potential energy curves agree well with those of the full-CI or MR-CI methods..
115. Haruyuki Nakano, Quasidegenerate perturbation theory with multiconfigurational self-consistent-field reference functions, The Journal of Chemical Physics, 10.1063/1.465674, 99, 10, 7983-7992, 1993.01, A quasidegenerate perturbation theory based on multiconfigurational self-consistent-field (MCSCF) reference functions is derived. The perturbation theory derived here is for multistate, where several MGSCF functions obtained by the state-averaged MCSCF method are used as the reference and an effective Hamiltonian is constructed by perturbation calculation. The energies of states interested in are obtained simultaneously by diagonalization of the effective Hamiltonian. An explicit formula of the effective Hamiltonian through second order is derived as well as general formalism, and is applied to calculate potential curves of the system H2, Be-H2, CO, NO, BN, and LiF. The results agree well with those of full configuration interaction or multireference single and double excitation configuration interaction methods for both the ground and the excited states..