An ab initio study of the electronic spectrum of Zn2 including spin–orbit coupling

The ground state as well as low-lying excited states of the zinc-dimer are studied using ab initio calculations. Spectroscopic constants and potential curves from all-electron, multi-configurational second-order perturbation calculations are compared to coupled cluster including triples corrections and averaged coupled pair functional results as well as available experimental data. Scalar relativistic effects are included through the use of the one-electron Douglas–Kroll operator. Spin–orbit coupling is accounted for perturbatively using the atomic mean-field spin–orbit operator. Both scalar relativistic and spin–orbit transition dipole moments are presented. The importance of correlation of 3d-orbitals is demonstrated, and recommended values of spectroscopic constants for the ground state are provided.