The Influence of Anisotropic Thermal Vibrations on Absorptive Form Factors for High-Energy Electron Diffraction

Thermal diffuse scattering is the dominant contribution to the absorptive form factors in high-energy electron diffraction. So far, calculations have been limited to isotropic thermal vibrations. In this paper, a general formula is given for the absorptive form factors that fully accounts for anisotropic temperature factors. The resulting formula is based on the Einstein model and well suited for numerical evaluation. A case study shows that even slight deviations from isotropy lead to a strong directional dependence of the absorptive form factors.