Local field effects and a model dielectric response matrix ϵG,G′(q) for a covalent semiconductor

Abstract

AbstractA model for the microscopic dielectric response ϵG,G′(q) of a covalent semiconductor is proposed in which the effects of the localized and plane wave features of the band structure on the polarizability are separated. Within this model for diamond a calculation is performed of the static longitudinal wave vector dependent macroscopic dielectric function ϵM(q), including local field corrections, together with an analysis in real space of the microscopic local field E(r) and polarization charge density ϱindr) induced by a uniform externally applied electric field. The results indicate that although the macroscopic dielectric function is essentially insensitive with respect to small changes in the effective charge model parameter Z, microscopic quantities such as the induced charge density and microscopic local field can be fairly sensitive to variations in Z. This suggests that careful tests on model based dielectric responses ϵG,G′(q) are probably necessary before one calculates, for instance, phonon frequencies.