Abstract
Tight-binding parameters for several diamond and zinc-blende II-VI and III-V materials are obtained and analyzed. The parameters are then utilized in a cluster model to locate the position of one-electron levels of vacancies relative to the band edges of the lattice. A value for the displacement energy of an atom from the cluster is obtained. Finally reasons why vacancy defect levels are likely to be affected by lattice distortion are discussed in light of the results of the cluster model.