Pair distribution function and x-ray absorption signatures of rotational and radial local distortions in a model system with average long-range order

The signatures of local distortions in three-dimensional crystalline struct ures are studied by calculating extended x-ray absorption fine structure (E XAFS) spectra and pair distribution functions (PDF) from a binary system wi th several different concentrations of randomly distributed radial, rotatio nal, or buckling static distortions. The PDF and EXAFS are examined to dete rmine if unique signatures for the different distortion scan be obtained. I t is shown how the complementarity of the PDF and EXAFS data can be used to effectively separate the radial from the rotational local distortions. [S0 163-1829(98)04445-2].