The Green function approach to the surface lattice dynamics of ionic crystals

Abstract

The Green function approach to the surface dynamics of semiinfinite lattices is developed in detail and shown to be applicable to crystals with long-range interionic potentials. Such applicability stands on the use of an effective short range perturbation, uniquely defined by the imposition of the translational and rotational invariance conditions for the stress-free semiinfinite crystal. Numerical calculations of the surface dispersion curves and of the surface projected phonon densities of NaCl, LiF and NaI, based on the breathing shell model, are reported and discussed.