The DIRDIF scaling procedures; rescaling for structures showing superstructure effects

Abstract

Abstract The DIRDIF program system for solving crystal structures using Patterson procedures and direct methods applied to difference-structure factors, uses a variety of X-ray intensity scaling procedures based on the formulae of Wilson (1942), and when part of the structure is known, Parthasarathy (1966), and Gould, Van den Hark and Beurskens (1975). Applications of these procedures to various heavy atom structures are discussed. A new scaling procedure is presented which is based on the relative frequency of calculated partial structure factors being larger than the observed structure factors on an absolute scale. This procedure is especially useful for structures with superstructure effects.