Quasirelativistic valence ab initio calculation of the potential curves for the Zn–rare gas van der Waals molecules Original Research Article

Results of large scale valence ab initio calculations of the potential curves for the ground and several low lying excited states of the Zn–rare gas (RG) van der Waals molecules are reported. In the calculations, the Zn20+ and RG8+ cores are replaced by energy-consistent pseudopotentials which also account for scalar-relativistic effects and spin–orbit (SO) interaction. Potential energies in the ΛS coupling scheme have been obtained by means of valence ab initio complete-active-space multiconfiguration self-consistent-field (CASSCF)/complete-active-space multireference second-order perturbation theory (CASPT2) calculations. On the other hand, the corresponding SO matrix has been calculated in a reduced CI space restricted to the CASSCF level. The final Ω potential curves are obtained by diagonalization of the modified SO matrix (its diagonal elements before diagonalization substituted by the corresponding CASPT2 eigenenergies). The calculated potential curves, and particularly the derived spectroscopic parameters De, Re and ωe for the ground and excited states of the Zn–RG complexes are discussed in the context of available experimental data. Quite reasonable agreement between the theoretical results and experimental data has been obtained for all Zn–RG pairs.