Haruyuki Nakano

Abstract: 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 MCSCF 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.

TL;DR: A quasidegenerate perturbation theory (QDPT) with Epstein-Nesbet partitioning based on MCSCF reference functions is presented in this paper, where the formulas for CSF-based matrix operations are derived.

TL;DR: In this paper, the multireference Moller-Plesset perturbation (MRMP) theory with complete active space self-consistent field (CASSCF) reference functions is applied to the study of the Q and B bands of free-base, magnesium, and zinc porphyrins and their derivatives.

TL;DR: In this article, a multireference perturbation theory with complete active space self-consistent field (CASSCF) reference functions is applied to the study of the valence ππ* excited states of 1, 3-butadiene, 1,3, 5-hexatriene, and 1, 5, 7-octatetraene.

TL;DR: In this article, a multireference perturbation theory with complete active space self-consistent field (CASSCF) reference functions was applied to the study of the valence π→π* excited states of benzene and naphthalene.