Lattice dynamics of graphite slabs

Abstract

Finely divided graphite is one of the most useful materials for a wide variety of adsorption studies. As a major step in our investigations of the theoretical description of such adsorption phenomena, we present here full dynamical calculations of bulk graphite and of graphite slabs consisting of a finite number of (0001) graphite planes. An extended version of the axially symmetric model of Nicklow, Wakabayashi, and Smith allows the appearance of surface modes of vibration not found with simpler models. Six branches of surface modes are found, but the surface modes are much less pronounced than those in more isotropic crystals as a result of the very weak interaction between the planes. We also present the bulk and slab vibrational density-of-states functions.