Size and Surface Effects on the Phonon Properties of Small Particles

Abstract

Measurements on thin films and surfaces have generated a need for a technique whereby one can calculate the phonon properties of small particles containing only a few hundred atoms. We have used moleculardynamic techniques to calculate the frequency distribution and various moments for five different particle configurations. Results are compared with the bulk solid. A model extending the Lennard-Jones and Devonshire cell model to surface environments is described. It is shown that this model replicates features of the more exact calculation. The frequency spectrum and various correlation functions are decomposed into contributions from the bulk, surface, and edge of a particle. The differences can be explained in terms of the local environment.