Phonon calculations in superperiodic structures: The surface Green-function matching approach

Abstract

We outline the practical implementation of the recently developed surface Green-function matching analysis to study phonons in superlattices and intercalated materials. The one-dimensional case is studied analytically and used for two applications. One would correspond to longitudinal phonons in Ag/Al superlattices, with good lattice-parameter matching and large mass ratio. This demonstrates the role of the interactions at the interface, especially manifested in the local density of states. The other application is the case of graphite intercalation compounds. Good agreement with inelastic-neutron-diffraction data for ${\mathrm{C}}_{\mathrm{n}}$K is obtained in terms of a physically plausible force-constants model.