Accurate calculations of the ground state and low-lying excited states of the (RbBa)+ molecular ion: a proposed system for ultracold reactive collisions

S Knecht (1) , L K Sørensen (1) , H J Aa Jensen (2) , Timo Fleig (3) , C M Marian (1)

1 Department of Theoretical Chemistry
2 Department of Physics and Chemistry
3 GMO - Groupe THEO (LCPQ)

calculations of the ground state and low-lying excited states of the (RbBa) + molecular ion, a proposed system for ultracold reactive collisions Abstract. Collisions of ultracold Ba + ions on a Rb Bose-Einstein condensate have been suggested as a possible benchmark system for ultracold ion-neutral collision experiments. However, a priori knowledge of the possible processes is desirable. For this purpose we here present high-level four-component coupled cluster and multi-reference configuration interaction calculations of potential energy curves, dipole moments, and spectroscopic constants of the experimentally interesting low-lying electronic states of the (RbBa) + molecule. Our results show significant avoided crossings between the 3 Σ + 1, 0 − Rb + Ba + entrance channels and low-lying charge transfer 3 Π 1, 0 − states of the Rb + and Ba 6s 1 5d 1 (3 D) atomic channels, indicating that a fast non-radiative charge transfer is possible. Population analysis shows that a partially covalent polar bond is formed in the ground state, which thus deviates significantly from a pure Rb + + Ba interaction. This finding is corroborated by the electric dipole moment which is found only to be 4.5 D at the equilibrium bond distance, compared with the 14 D for a pure Rb + + Ba interaction, thereby supporting the view of a partial charge transfer between the two atoms.

Mots clés: 34.70.+e; 31.15.aj; 31.15.ag; 31.15.ae; 31.15.vn; 31.15.vj; 33.15.Fm; 31.15.am; 31.15.bw

Domaines: Physique [physics]

S Knecht, L K Sørensen, H J Aa Jensen, Timo Fleig, C M Marian. Accurate calculations of the ground state and low-lying excited states of the (RbBa)+ molecular ion: a proposed system for ultracold reactive collisions. Journal of Physics B: Atomic, Molecular and Optical Physics, 2010, 43 (5), pp.55101. ⟨10.1088/0953-4075/43/5/055101⟩. ⟨hal-00569870⟩