The dielectric constant of cubic IV-VI compounds

Abstract

The electronic part of the dielectric constant epsilon infinity is calculated using a simple analytical model. The technique involves the use of the f sum rule to evaluate most of the detailed band structure information, and is closely related to the Penn model of an isotropic semiconductor in the use of this method, although the present technique is quite valid for the strongly anisotropic IV-VI materials. Local fields are included through the off-diagonal elements of the dielectric matrix epsilon (G, G') and are shown to be important. The results reproduce the experimental trends of epsilon infinity down the series and are in good agreement with experiment.