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Can a multipole analysis faithfully reproduce topological descriptors of a total charge density?
Acta Cryst. (2002). A58, 451–459
Ian Bytheway, Graham S. Chandler and Brian N. Figgis
Using a multipole expansion to extract a charge-density distribution from X-ray data is known to show disagreement with theoretical calculations of the same density. The origin of these differences has been attributed to various causes. This paper examines the accuracy of the multipole fitting itself by starting from a precisely known density for crystalline ammonia. This charge density is transformed into thermal-motion-free structure factors, which are then fitted using the usual techniques of multipole analysis.