Role of semicore electrons in the lattice dynamics of a cubic ZnS crystal

The phonon dispersion in a ZnS crystal has been studied by the density functional theory method with different pseudopotentials containing 10 (Zn¹²⁺) and 18 (Zn²⁰⁺) semicore electrons of the shell with the principal quantum number n = 3 in a zinc atom. It has been found that the pseudopotential of Zn²⁰⁺, unlike the pseudopotential of Zn¹²⁺ describes the phonon dispersion more accurately. An analysis has demonstrated that, in this case, the degree of d-p hybridization of semicore d states of zinc with the valence p states of sulfur decreases.