Surface dielectric response of a semimetal: Electron-energy-loss spectroscopy of graphite

Abstract

The surface-dielectric-response function is important in describing a wide range of many-body properties of surfaces. Previous calculations of this quantity have assumed a free-electron metal surface, treated in a jellium approximation. Here we present calculations of the dielectric-response function of a graphite surface. These calculations show that the dielectric behavior of the graphite surface is quite different from that of simple metals. Using the calculated surface dielectric function we obtain theoretical electron-energy-loss spectra of graphite in the 0–1.4 eV range, which compare well with the experimental data. The spectra have a number of unusual features that are shown to be consequences of the semimetallic band structure and the kinematics of the dipole-scattering theory.