Cluster model and calculation of the electronic structure of covalent solids

The possibilities of the cluster model for describing the electronic structure of multielement and composite amorphous substances have been examined. The calculation scheme developed gives the local density of electronic states for a cluster after it has been matched to the remaining medium in the coherent-potential approximation, making it possible to take into account local violations of the short-range order and to thereby simulate various structural defects. Multicomponent chalcogenide glasses are represented by the cluster model as a set of fundamental structural units found in a structural matrix of the substance under study with different weights. The results of calculations of the density of electronic states for silicon, arsenic, selenium, and binary chalcogenic glasses of the type As/sub x/Se/sub 1-x/, as well as the possibilities of the interpretation of photoinduced processes in the framework of the cluster model, have been discussed