Electronic states of CsLi and CsLi+ molecules

Abstract

Configuration interaction calculations have been carried out on electronic states of the CsLi molecule and the CsLi+ cation. Adiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels are presented for the lowest states of 1,3Σ+, 1,3Π, and 1,3Δ symmetries of the alkali dimer CsLi molecule dissociating into Cs (6s, 6p, 5d, 7s, and 7p) + Li (2s, 2p, 3s, 3p, and 3d) as well as for the lowest 2Σ+, 2Π, and 2Δ electronic states of the CsLi+ cation dissociating into Li (2s, 2p, 3s, 3p, and 3d) + Cs+ and Li+ + Cs (6s, 6p, 5d, 7s, and 7p). The results of the present many-electron configuration interaction calculations on the cation support the previous core-polarization effective potential calculations. The present calculations on the CsLi molecule are complementary to previous theoretical work on this system, including recently observed electronic states that had not been calculated previously. We have used an ab initio approach involving a nonempirical pseudopotential for the Li (1s2) and Cs cores and a core-valence correlation correction. A very good agreement of data from spectroscopic constants for some of the lowest states of the CsLi and CsLi+ molecules with those available in recent theoretical works has been obtained. The existence of numerous avoided crossings between electronic states of 2Σ+ and 2Π symmetries is related to a charge transfer process between the two ionic CsLi+ and LiCs+ systems.