Theoretical calculation of the electronic states with spin-orbit effects of the molecule LiCs

The potential energy curves of the molecule LiCs have been calculated for the 55 low-lying electronic states in the U-representation. Using an ab initio method the calculation is based on a nonempirical pseudo-potential in the interval 3.0_ao ≥ R ≥ 40.0_ao of the internuclear distance. The spin-orbit effects have been taken into account through a semi-empirical spin-orbit pseudo-potential added to the electrostatic Hamiltonian with Gaussian basis sets for both atoms. The spectroscopic constants have been calculated for 39 states and the components of the spin-orbit splitting have been identified for the states (2, 5) ³Π and (1) ³Δ. The comparison of the present results with those available in literature shows good agreement, while the other results, to the best of our knowledge, are given here for the first time.