Enhanced Efficiency of Direct-Space Structure Solution from Powder X-ray Diffraction Data in the Case of Conformationally Flexible Molecules
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- 作者：Andrew J. Hanson ; Eugene Y. Cheung ; Kenneth D. M. Harris
- 刊名：Journal of Physical Chemistry B
- 出版年：2007
- 出版时间：June 14, 2007
- 年：2007
- 卷：111
- 期：23
- 页码：6349 - 6356
- 全文大小：375K
- 年卷期：v.111,no.23(June 14, 2007)
- ISSN：1520-5207
文摘
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 inparticular on the genetic algorithm technique for structure solution in which fitness is defined as a functionof the whole-profile figure-of-merit Rwp. The strategy employs a readily computed distance-based function toassess the feasibility of the molecular conformation in each trial structure generated in the genetic algorithmcalculation, and structures considered to have low-feasibility conformations are penalized within the evolutionaryprocess. The strategy is shown to lead to significant improvements in the success rate of structure-solutioncalculations in the case of flexible molecules with a significant number of conformational degrees of freedom.