Theoretical study of the Ca+ − He ionic system with spin–orbit coupling

Abstract

We have performed ab-initio calculations to investigate the van der Waals interaction between a Ca+ ion and a helium atom. We have focused on determining the low-lying electronic states of the Ca+−He ionic system using advanced theoretical methods, including RCCSD(T) and SA-CASSCF/MRCI , with the incorporation of Davidson and BSSE corrections. Furthermore, we have considered the impact of spin–orbit coupling SO on these states using the state-interacting method. Spectroscopic parameters of the potential energy curves PECs were calculated and compared with existing data from previous studies. Additionally, we have evaluated vibrational levels, their spacing, radiative lifetimes, transition dipole moments TDMs and permanent electric dipole moments PDMs. The position of satellites in the absorption spectra of white dwarfs was determined. Our results were compared with available theoretical and experimental data to assess their accuracy and agreement. This study provides valuable insights into the van der Waals interaction and electronic properties of the Ca+−He ionic molecule.