Molecular dipole model of internal optic modes

Abstract

The internal optic modes of a crystal are discussed, first using the diagonalized dynamical interaction matrix formalism and then in terms of a molecular dipole model which is more familiar to molecular spectroscopists. The relationship between the two methods is discussed. The approximations that are made to derive the molecular dipole model result in a description that includes interactions between the optic branches. As a further result of these approximations the internal optic mode dispersion curves are wave vector dependent only through the dipolar coupling terms.