Abstract

Explicitly representing the deformation of ions by the lattice dynamical shell model, the one-phonon scattering is written in a form that is amenable to direct evaluation. An analytic expression for the shell scattering factor is introduced, and the percentage alteration in the scattering brought about by the ionic deformation during vibration is calculated. Contour plots of the effect are presented for GaAs, ZnS and Si as representative of the zinc-blende-structure compounds and group IV elements. The alteration produced by shell models is found to be negative, because for these materials the shell moves less than the core. Its maximum value varies from about -2.5 to -15% depending on the material and lattice dynamical model used. Its structure in reciprocal space should be measurable and could lead to a better understanding of deformation processes.