Kizashi Yamaguchi

TL;DR: In this paper, the UKS DFT was applied to the calculation of potential curves and effective exchange integrals (Jab) for open-shell species, and it was found that the potential curves for the singlet state for the dimer of triplet CH2 were deeper than those of ab initio second-order CI and CASPT2(D) and therefore the Jab value for (CH2)2 was several times larger in the region R > 3.2 A than the corresponding AB initio value.

TL;DR: In this paper, various size-consistent approaches to the calculation of molecular hyperpolarizabilities are analyzed based on the double perturbation theory and the coupled cluster theory.

TL;DR: In this paper, the potential energy curves of several hydrogen clusters (H 2 -H 6 ), hydrogen fluoride and fluorine molecules were compared by depicting potential energy curve of several spin-restricted and spin-unrestricted post-Hartree-Fock methods.

TL;DR: In this paper, an approximate formula for virtual excitation processes (three-type approximate formula) describing the third-order hyperpolarizability (γ) is rewritten by the use of polarizabilities of the ground and excited states (α0, αn), and a criterion for a classification of γ for organic compounds is drawn from the formula.

TL;DR: Spin-restricted and unrestricted post-Hartree-Fock calculations were carried out for clusters of triplet methylene and nitroxide radicals in this paper, where the UHF-based methods such as UMP and QCISD followed by approximate spin projection provided reasonable energy differences between the high and low-spin states of these species.