Implications of X-ray thermal diffuse scattering in integrated Bragg intensities of silicon and cubic boron nitride

Abstract

This article describes a theoretical quantification of the thermal diffuse scattering (TDS) contribution to the integrated intensities of single-crystal diffraction from silicon and cubic boron nitride. The TDS intensity is calculated ab initio and the intensity contribution to the Bragg peak determined by integration of a volume of appropriate size. The effect of including TDS in the structure factors is assessed in a subsequent refinement, where the effect on the atomic displacement parameters and the residual Fourier maps is inspected. In both compounds changes caused solely by the TDS inclusion are observed. Particularly, adding TDS to the structure factors of silicon produces significant features in the residual Fourier maps and a change in the atomic displacement parameter. Significant effects are also present at low temperatures. Thus, it is important to address the effect of TDS when pursuing high-accuracy charge densities or if analyzing the atomic displacement parameters.The thermal diffuse scattering (TDS) contribution to the integrated Bragg intensities is calculated and quantified, and the implications of uncorrected TDS for crystallographic models investigated.