The electronic structure and spectroscopy of V2

The electronic structure and spectroscopy of the vanadium dimer has been studied with semiempirical self-consistent field-configuration interaction calculations using the intermediate neglect of differential overlap Hamiltonian parameterized for spectroscopy (INDO/S) including spin–orbit coupling effects. An approximate configuration interaction (CI) treatment is designed based on correlation effects observed in CI calculations in small active spaces, and yields good agreement with experimental observations of state energies and spin-orbit splittings. The location of a 1Σg+ excited state isoconfigurational with the ground state was determined, and calls into question a previous assignment of an excited state observed near 1860 cm−1. The previously observed A 3Πu←X 3Σg− transition is assigned as a dδg←dπu promotion. In addition, an unassigned transition observed near 15 000 cm−1 has been assigned as B 3Σu−←X 3Σg−. Both this transition and the previously observed A′ 3Σu−←X 3Σg− transition are assigned as σu←σg promotions, in disagreement with previous assignments. A 1Σu+ state isoconfigurational with the A′ 3Σu− state is suggested as a candidate for an unassigned transition in the range 11 250–12 500 cm−1.