Toward EXPO: From the Powder Pattern to the Crystal Structure

Recently devised techniques for powder pattern decomposition will be discussed: they exploit the supplementary information available during the phasing process, so improving by far the pattern decomposition and the crystal structure solution process. A new package, EXPO, integrates EXTRA [1], a Le Bail-based [2] full pattern decomposition program, with a new version of SIRPOW.92 [3], a direct methods package optimized for powder data. Different ways of combining various kinds of structural information will be discussed and some applications to test structures will be presented.