Model calculation of local-field corrections to the static dielectric properties of a covalent semiconductor

The wave-vector-dependent macroscopic response functions of diamond and silicon are calculated using a simple model for the static dielectric matrix of a covalent semiconductor. Local-field corrections are taken into account using a Wannier-function inversion technique in which the microscopic static dielectric response epsilon/sub GGprime/-1(q) is modeled by two mechanisms of screening, one corresponding to the response by a uniform homogeneous medium characterized by epsilon0(q+G) and the other by a set of dipoles interacting via the screened electron-electron interaction v(q+G)/epsilon0(q+G). Results for the static dielectric constant with and without local-field effects are compared to previous model calculations. The static microscopic dielectric response is tested in the long-wavelength limit via an analysis in real space of the microscopic local field and polarization charge density induced by a uniform externally applied electric field along the [111] direction