Interactions of transition metal atoms with He

Abstract

The adiabatic interaction potentials were obtained for the paradigm transition metal-rare gas interactions: Sc(2D)-He and Ti(3F)-He and their di-cations. The ab initio approach included the coupled cluster and multireference configuration interaction methods. He atoms form very weak van der Waals complexes with Sc and Ti with well-depths of ca. 4-5 cm-1. The interactions are characterized by the nearly-degenerate manifolds of adiabatic states with splittings of the order of 0.1 cm-1 or less. The anisotropy of the Ti-He interaction is smaller than that for the Sc-He interaction. The origin of the weak anisotropy of these interactions was analyzed. The exchange repulsion was found to be nearly the same in the \({\rm\Sigma}\), \({\rm\Pi}\) and \({\rm\Delta}\) states due to the valence d-electrons being submerged under the doubly filled 4s electron sub-shell. The anisotropy of the total potential is controlled by the weakly-anisotropic dispersion interaction.