ON THE APPLICATION OF ONE-WAVELENGTH ANOMALOUS SCATTERING .4. THE ABSOLUTE-CONFIGURATION OF THE ANOMALOUS SCATTERERS

An essential first step in most techniques for using anomalous-scatter ing data for phase determination is to determine the positions of the anomalous scatterers. This is usually done by use of the anomalous dif ferences, either as input to a direct-methods procedure or to produce a Patterson map. If the arrangement of anomalous scatterers is noncent rosymmetric then it is also necessary to find their absolute configura tion and a process is described for doing this based on the properties of the P-s function [Okaya, Saito and Pepinsky (1955). Phys. Rev. 98, 1857-1858]. If the arrangement of anomalous scatterers is centrosymme tric then the problem does not occur.