Equations for diffuse scattering from pseudobinary sphalerite F3m systems

The equations describing X-ray diffuse scattering in crystals with the pseudobinary sphalerite F3m structure (e.g. Hg_{1 - x}Cd_xTe and other pseudobinary semiconductors) are presented accurately up to the second order in local atomic displacements. This treatment considers the local properties from the noncentrosymmetric structure as well as complex scattering factors. The result contains additional terms related to the noncentrosymmetric crystal properties and the imaginary parts of the atomic scattering factors. Expressions are also presented that are applicable to an experiment involving difference anomalous dispersion techniques. Equations relating the various terms at symmetry-related points in reciprocal space are included as well as the least-squares method required to solve the matrix equations from diffraction data taken in a volume of reciprocal space.