title: A study of the ground state of manganese dimer using quasidegenerate perturbation theory.
abstract: 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 1Sigmag+, 11Sigmau+, and 11Piu states, which are candidates for the ground state. Of these states, the 1Sigmag+ state has the lowest energy and we therefore identify it as the ground state. We find values of 3.29 A, 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 A, 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.
authors.affiliation: Faculty of Liberal Arts, Chukyo University, 101-2 Yagoto-Honmachi, Showa-ku, Nagoya, Aichi 466-8666, Japan. syammaot@lets.chukyo-u.ac.jp
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tatewaki
authors.forename: Hiroko
authors.initials: H
authors.lastname: Moriyama
authors.forename: Haruyuki
authors.initials: H
authors.lastname: Nakano