Vibrational Properties of Imperfect Crystals with Large Defect Concentrations

The multiple-scattering theory of Lax is used to give equations for the displacement-displacement Green's functions for a crystal containing substitutional defect atoms. A self-consistent method is described within this formalism that is most suitable for large concentrations of mass defects. The essential approximation is best in three dimensions, but even then is not completely satisfactory for low concentrations of light defects. The …