Solving crystal structures from powder data .2. Pseudotranslational symmetry and powder-pattern decomposition

Pseudotranslational symmetry may be characterized by the performance of statistical calculations on the normalized structure factors. The efficiency of the method is quite high if single-crystal data are used. When only powder data are available, the characterization process is not straightforward; in this paper, it is shown how it can safely be done. The information so gained may be used as prior information in the pattern-decomposition process. It is shown that its use improves the estimates of the integrated intensities, with consequent benefit for the efficiency of the direct phasing process.