Ab initio correlation calculations for the ground-state properties of group-12 metals Zn and Cd

The group-12 metals zinc and cadmium have easily polarizable closed d shells and form unusual hexagonal close-packed structures which are not described by density functional calculations. We perform a wave-function-based correlation treatment on top of periodic Hartree-Fock calculations for these materials. This treatment corresponds to a many-body expansion of the correlation energy of the extended system in terms of localized orbital groups. This ansatz is the method of increments, which uses an embedding scheme for metals to model the metallic character. Although the Hartree-Fock treatment yields no binding and no equilibrium geometry for zinc and cadmium, the binding of the ground-state structure is fully described by electronic correlations. Our values of the cohesive energy agree within 8% with the experimental value and within 2% for the lattice parameters.