Tight-binding calculation of the properties of theFcenter and of isoelectronic defects in ZnS

Using a tight-binding parametrization of the band structure of ZnS, we calculate the energy levels of the $F$ center associated with a vacancy of S, and of some isoelectronic defects on Zn and S sites. The calculation is performed in a Koster-Slater scheme, using the Haydock, Heine, and Kelly recursion method to generate the Green's functions. The theoretical results agree reasonably well with the experimental data.