Ab initio calculations of electronic structure of the BaCs molecule: adiabatic potential energy curves, spectroscopic constants, spin–orbit effect and permanent and transition electric dipole moments

Abstract

An ab initio approach based on effective core potentials (ECPs), core polarization potentials (CPPs) with three valence electrons and multireference configuration interaction (MRCI) level of calculation is used to determine the adiabatic potential energy curves, the spectroscopic constants and the permanent and transition electric dipole moments of the lowest doublet and quartet electronic states of BaCs. These sates are dissociating into the first six asymptotic limits of the alkali–alkaline earth molecule, BaCs. Only the ground state has been studied in the literature, and the comparison with the available results has shown a very good agreement. The spin–orbit interaction has been included in the next step of our calculation, and its effect on the potential energy curves and spectroscopic parameters on the Ω representation states has been thoroughly studied. Both relativistic and nonrelativistic calculations of permanent and transition dipole moments are also presented, which allows us to determine the influence of relativistic effects on the dipole moment.