Phase determination from X-ray powder diffraction data. II. Partial Patterson maps and the localization of anomalously scattering atoms

Partial Patterson maps containing peaks from anomalous scatterers only can be derived from powder diffraction data. For each anomalous scatterer, three data sets are needed: one off the edge and another two at two wavelengths close to the edge. The method presented is based essentially on the wavelength dependence of the real part of the anomalous scattering factor.