Spherical harmonics analysis based on the Reuss model in elastic macro strain and stress determination by powder diffraction

In this paper a new approach to macro strain/stress analysis by generalized spherical harmonics is presented. It consists of expanding the stress tensor weighted by texture in a series of generalized spherical harmonics with the ground state of expansion specific to the classical Reuss model of an isotropic polycrystal. Like previously reported models having a ground state of hydro­static type [Popa & Balzar (2001). J Appl Cryst. 34, 187–195] and of Voigt type [Popa et al. (2014). J Appl Cryst. 34, 154–159], the actual model is appropriate for use with Rietveld refinement.