Aspects of validation in the structure determination of organic materials from powder X-ray diffraction data

Techniques for structure determination of organic materials from powder X-ray diffraction data are now applied widely in many different fields of scientific research. Nevertheless, structure determination from powder diffraction data is far from,in automatic, "black-box" process, and it is essential that the results obtained frorn such analysis are subjected to adequate Scrutiny before they are assigned to be valid and correct. Here we consider two aspects of validation relevant to this field: (i) validation of the structural model used in direct-space structure solution calculations, and (ii) validation of the final structure obtained from Rietveld refinement. The advantages of exploiting information obtained frorn other experimental and computational techniques are emphasized.