A comparative density functional study of the low pressure phases of solid ZnX, CdX, and HgX: trends and relativistic effects.

A comprehensive density functional study of the group 12 chalcogenides has been carried out to study the impact of relativistic effects on the solid-state and electronic structure of the mercury chalcogenides in order to explain their unique behavior compared to the lighter group 12 congeners. For this, we present scalar-relativistic and nonrelativistic density functional calculations for several crystal structures commonly occurring in ZnX, CdX, and HgX (X = S, Se, and Te). The cohesive energies and other ground-state properties (at the zero-temperature limit) are obtained to identify the low-pressure phases and to discuss relativistic effects. Relativistic crucially influences the crystal structure in HgS, an effect less pronounced in the heavier chalcogenides HgSe and HgTe. However, for HgSe and HgTe we find that relativistic effects have a major impact on the electronic structure, where the change upon neglect of relativity goes as far as to the restoration of semiconducting properties.