UACIEM: A new method to extract reliable intensities of nonequivalent systematical overlapping reflections from powder diffraction data

A new method, namely UACIEM, to extract reliable intensities of nonequivalent systematical overlapping reflections has been proposed and tested by simulated powder diffraction data from known crystal structures. Using both crystallographic and structural chemistry information, the method reconstructs diffraction intensities and solves a crystal structure through an iterative procedure. Our study shows that UACIEM is successful for cases where more than 30% of the total scattering power is located with precision from equivalent systematical overlapping reflections. The UACIEM process is not needed when equivalent systematical overlapping reflections are sufficient to reveal a crystal structure. UACIEM may fail in cases when: (i) only a small portion of the total scattering power (e.g., less than 7%) can be located, and (ii) most of the total scattering power (e.g., 95%) is located, but the atomic coordinates are not accurately known. The UACIEM method is superior to the simple equipartition methods for nonequivalent systematical overlapping reflections. (C) 2004 International Centre for Diffraction Data.