Theoretical study of LiK and LiK+ in adiabatic representation

Abstract

The potential energy curves have been calculated for the electronic states of the molecule LiK within the range 3 to 300 a.u., of the internuclear distance R. Using an ab initio method, through a semiempirical spin-orbit pseudo-potential for the Li (1s2) and K (1s22s22p63s23p6) cores and core valence correlation correction added to the electrostatic Hamiltonian with Gaussian basis sets for both atoms. The core valence effects including core-polarization and core-valence correlation are taken into account by using an l-dependent core-polarization potential. The molecular orbitals have been derived from self-consistent field (SCF) calculation. The spectroscopic constants, dipole moments and vibrational levels of the lowest electronic states of the LiK molecule dissociating into K (4s, 4p, 5s, 3d, and 5p) + Li (2s, 2p, 3s, and 3p) in 1, 3Σ, 1, 3Π, and 1, 3Δ symmetries. Adiabatic results are also reported for 2Σ, 2Π, and 2Δ electronic states of the molecular ion LiK+ dissociating into Li (2s, 2p, 3s, and 3p) + K+ and Li+ + K (4s, 4p, 5s, 3d, and 5p). The comparison of the present results with those available in the literature shows a very good agreement in spectroscopic constants of some lowest states of the LiK and LiK+ molecules, especially with the available theoretical works. The existence of numerous avoided crossing between electronic states of 2Σ and 2Π symmetries is related to the charge transfer process between the two ionic systems Li+K and LiK+.