Local Field Correction and Acoustic Sum Rule for Si and Ge

Abstract

The microscopic inverse dielectric matrix in the limit of a long wavelength is calculated in the random phase approximation for Si and Ge by using the realistic band models. It is shown that, if a proper form of the pseudopotential is employed, the acoustic sum rule can be substantially satisfied without any adjustable parameter, and the local field correction to the static dielectric constant can not be neglected.