THE DIRDIF SCALING PROCEDURES - RESCALING FOR STRUCTURES SHOWING SUPERSTRUCTURE EFFECTS

The DIRDIF program system for solving crystal structures using Patters on procedures and direct methods applied to difference-structure facto rs, uses a variety of X-ray intensity scaling procedures based on the formulae of Wilson (1942), and when part of the structure is known, Pa rthasarathy (1966), and Gould, Van den Hark and Beurskens (1975). Appl ications of these procedures to various heavy atom structures are disc ussed. A new scaling procedure is presented which is based on the rela tive frequency of calculated partial structure factors being larger th an the observed structure factors on an absolute scale. This procedure is especially useful for structures with superstructure effects.