The group 12 metal chalcogenides: an accurate multireference configuration interaction and coupled cluster study

Abstract

The near-equilibrium potential energy functions of the lowest two electronic states (1Σ+, 3Π) of the group 12 chalcogenides, i.e. {Zn, Cd, Hg} + {O, S, Se, Te, Po}, have been calculated from large-scale multireference configuration interaction (MRCI) and coupled cluster calculations. Use of a sequence of correlation consistent basis sets with accurate relativistic pseudopotentials allowed for the extrapolation of the potential functions to the complete basis set (CBS) limit. Inclusion of spin–orbit coupling yields an avoided crossing between the Ω = 0+ components of the 1Σ+ and 3Π states, which in some cases strongly affects the ground state spectroscopic constants. In almost all cases the calculated ground electronic state corresponds to , except for CdPo, HgSe, HgTe, and HgPo, where the 3Π2 state is calculated to be lowest. Spectroscopic constants and dissociation energies are determined for all states both before and after the inclusion of spin–orbit coupling. Accurate equilibrium dipole moments (without spin–orbit effects) are also reported for the 1Σ+ states. The present work confirms that the dissociation energies of all the group 12 chalcogenides except ZnO should be revisited by experiment.