Crystallography Research Today is a free monthly online journal that collates and summarizes the latest research about Crystallography, including details on x-ray crystals, techniques, analyses, structures.

Enhanced efficiency of direct-space structure solution from powder X-ray diffraction data in the case of conformationally flexible molecules.

Hanson AJ, Cheung EY, Harris KD

School of Chemistry, Cardiff University, Park Place, Cardiff, CF10 3AT Wales, UK.

A strategy is reported for assessing the feasibility of molecular conformations within direct-space structure-solution calculations of organic molecular crystal structures from powder X-ray diffraction data, focusing in particular on the genetic algorithm technique for structure solution in which fitness is defined as a function of the whole-profile figure-of-merit Rwp. The strategy employs a readily computed distance-based function to assess the feasibility of the molecular conformation in each trial structure generated in the genetic algorithm calculation, and structures considered to have low-feasibility conformations are penalized within the evolutionary process. The strategy is shown to lead to significant improvements in the success rate of structure-solution calculations in the case of flexible molecules with a significant number of conformational degrees of freedom.

Published 7 June 2007 in J Phys Chem B, 111(23): 6349-56.
Full-text of this article is available online (may require subscription).

© 2005-2008 Crystallography Research Today. All Rights Reserved.