Multi-reference perturbation theory study on the RaCl molecule promising for the laser cooling

Abstract

The potential energy curves of the ground and eight low-lying excited atomic and ionic terms of the RaCl molecule are calculated for the first time using the multi-reference perturbation theory method at the CASSCF/XMCQDPT2 level of theory including the spin-orbit coupling. The electronic term energies, equilibrium internuclear distances, dissociation energies, transition dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The data obtained in this study suggests the possibility of the direct laser cooling of the RaCl molecules.