Local field effects in the dynamical response of Ag

Abstract

We evaluate the local field effect for an Ag crystal within the "Swiss cheese" model employing different approximations for the intra-band screening. In this model the inter-band transitions are modeled through polarizable entities with appropriate polarizability localized at the lattice sites of the crystal. Their mutual interactions are screened by the dielectric response of the conduction electrons. We assume a homogeneous electron gas described by either nonlocal hydrodynamic or Lindhard dielectric functions or by a local Drude response. We calculate the screened dipole-dipole interaction tensor and find that it increases with the degree of spatial dispersion. We identify the local field effects on the macroscopic dielectric function and conclude that they depend very strongly on the non-locality of the intra-band screening.