Thermal diffuse scattering in integrated intensities of Bragg reflections

Two programs have been developed to calculate the one-phonon thermal diffuse scattering included in measured integrated intensities of Bragg reflections for cubic crystals. Both include the anisotropy of the diffuse scattering correctly within the continuum elasticity approximation, and both allow an approximate inclusion of the effects of the wavelength distribution of the primary beam. One program, restricted to ω-scans, includes primary beam divergences approximately using three experimental reflection profiles to describe the weighting function in reciprocal space. The second program, applicable to both ω-scans and θ: 2θ-scans, neglects the primary beam divergences but has the advantage of being approximately two orders of magnitude faster than the first. Calculations have been made with these programs for several cases to illustrate the dependence of the included thermal diffuse scattering correction on various factors and to compare with the values obtained from previous approaches.