Multireference configuration interaction study on the potential energy curves and radiative lifetimes of low-lying excited states of CdH+ cation

- The excited states of CdH+ have been studied by multi-configuration wavefunctions.
- The SOC effect on CdH+ is accounted for via state interaction method.
- Our spectroscopic results support the early experimental data.
- The PDMs and SO matrix elements reveal the abrupt changes at RACP.
- The abrupt changes are explained with the aid of the wavefunctions.

Ab initio calculations on CdH+ cation have been performed with the high-level relativistic MRCI + Q method. The potential energy curves of seven low-lying Λ-S states, correlated with the dissociation limits Cd+(2Sg) + H(2Sg), Cd(1Sg) + H+(1Sg), and Cd+(2Pu) + H(2Sg), are computed. And the accurate spectroscopic constants of the bound Λ-S are determined. The permanent dipole moments (PDMs) of Λ-S states as well as the spin-orbit matrix elements are evaluated. The results indicate that the abrupt changes of PDMs and the spin-orbit matrix elements are attributed to the change of the electronic configurations at the avoided crossing point. After considering the spin-orbit coupling (SOC) effect, the 12 Ω states generated from the Λ-S states are investigated. It is indicated that the SOC effect is substantial for CdH+, leading to the double-well potential of (3)0+ state. Finally, the transition properties of several transitions are reported, including the transition dipole moments, Franck-Condon factors, and radiative lifetimes.