The University of Osaka · Biochemistry, Genetics and Molecular Biology
Professor Kizashi Yamaguchi's research lab specializes in theoretical and computational quantum chemistry, focusing on the electronic structure and magnetic interactions in transition metal oxides, biomimetic clusters, and organic magnetic systems. The lab employs advanced ab initio and density functional theory methods to investigate spin-coupling mechanisms, exchange interactions, and electronic properties relevant to high-Tc superconductivity, water oxidation in photosystem II, and organic radical-based magnetism. A central theme is the development and application of generalized molecular orbital and Hubbard model approaches to understand broken-symmetry states and polyradical character in complex molecular systems.
Figures are computed from collected data and may differ slightly.
The superexchange interaction between transition-metal ions via oxygen dianion was investigated by the ab initio molecular orbital (MO) method. It is found that the magnitude of the effective exchange integral ( J ab ) for the CuOCu unit is far larger than those of the NiONi, CrOCr and FeOFe units. Implications of this result are discussed in relation to the high T c superconductivity for Ba-La-Cu-O and R-Ba-Cu-O (R=Y, etc.).
Abstract A generalized molecular orbital (GMO) theory for magnetically interacting organic compounds has been presented. The theory is applied to the calculations of the effective exchange integrals (Jab) for the cyclophane-type carbene dimers whose para and ortho-isomers have the high-spin ground state. The calculated Jab-values are consistent with observations.
Full geometry optimizations of several inorganic model clusters, CaMn(4)O(4)XYZ(H(2)O)(2) (X, Y, Z = H(2)O, OH(-) or O(2-)), by the use of the B3LYP hybrid density functional theory (DFT) have been performed to illuminate plausible molecular structures of the catalytic site for water oxidation in the S(0), S(1), S(2) and S(3) states of the Kok cycle for the oxygen-evolving complex (OEC) of photosystem II (PSII). Optimized geometries obtained by the energy gradient method have revealed the degree
Abstract Analytical expressions of total energies, effective exchange integrals, polyradical character, spin density, unpaired electron density, and information entropy are derived for allyl radical dimers and trimers on the basis of the Hubbard model in order to elucidate interrelationships among several broken‐symmetry and symmetry‐adapted approaches to molecular magnetism. Ab initio unrestricted Hartree–Fock and hybrid density functional theory (DFT) calculations of allyl radical dimers to de
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