Anisotropic Thermal Vibrations and Dynamical Electron Diffraction by Crystals

The effect of anisotropy in thermal vibrations on dynamical electron diffraction by a crystal is investigated. Expressions are first derived for both the elastic and thermal diffuse scattering (TDS) absorptive atomic scattering amplitudes for the general case of anisotropic thermal vibrations. These expressions are then used to calculate the complex structure factors for an SrTiO 3 single crystal at 293K. It is shown that the errors introduced by using an averaged Debye-Waller factor are typically of the order 1-5% for low- and mediumorder reflections.