Theoretical study of the electronic structure of the transition metal dimers, Sc2, Cr2, Mo2 and Ni2

Abstract

MCSCF calculations of the potential energy curves of the ground states of the transition metal species Sc2, Cr2, Mo2 and Ni2 are described. The ground state of Sc2 is calculated to be 5∑–u, corresponding to the orbital occupancy σ2g(s)σ1g(d)π2u(d)σ1u(s). In Ni2 the metal–metal bonding is due to the doubly occupied σg(s) orbital, a number of very closely spaced states arising from the weakly interacting pair of nickel d9 configurations. In Cr2 and Mo2 a major feature of the bonding is the reduction in the order of the “sextuple” bond due to correlation effects, particularly in Cr2. Binding energies of all four diatomic species are calculated and compared with available experimental data.