  An approach combining the Rietveld method and pairs distribution function
analysis was developed and can help to understand the effect of temperature
and/or high-pressure on crystalline materials. It was applied to orthorhombic
Ta2O5 compound, and the obtained results were compared with the experimental
pairs distribution function reported in the literature, and an excellent
agreement was reached. The approach permitted to simulate average pairs
distribution functions GTa-Ta(R), GTa-O(R), and GO-O(R) and the average radial
distribution functions RDFTa-Ta(R), RDFTa-O(R), and RDFO-O(R). The coordination
numbers for the first neighbors were obtained, and used in the expression to
calculate the Cowley-Warren chemical short-range order parameter {\alpha}CW .
The calculated value suggests a preference for forming homopolar pairs in the
first coordination shell. Previous study on the effect of high-pressure on
orthorhombic Ta2O5 showed a pressure-induced amorphization process. This
amorphization can be associated with the preference for forming homopolar pairs
in the first coordination shell.
