Theoretical electronic structure with rovibrational calculations of the alkali chloride molecules XCl (X = Li, Na, K, Rb, Cs)

Abstract

The adiabatic potential energy curves and the static dipole moment curves of the low-lying singlet and triplet electronic states in the representation 2s+1Λ(+/−) of the five alkali chloride molecules (LiCl, NaCl, KCl, RbCl and CsCl) have been investigated via ab initio calculations using the state averaged complete active space self consistent field followed by the Multi-reference single and double configuration interaction method with Davidson correction CASSCF/(MRCI + Q). For the molecules under consideration, the spectroscopic constants Te, Re, ωe and Be, the dipole moment μe, and the dissociation energy De have been calculated for the bound states along with the percentage ionic character fionic around the equilibrium position of the ground state. Moreover, the transition dipole moment curves of the X1∑+–(2)1∑+ and X1∑+–(1)1Π transitions have been investigated for the five alkali chloride molecules. A rovibrational calculation was carried out using the canonical functions approach in order to determine the rovibrational constants Ev, Bv and Dv and the abscissas of the turning points Rmin and Rmax for the investigated bound states.