Rietveld refinement, rigid-body

Powder diffraction techniques have become increasingly useful as tools for crystal structure determination especially in cases where it is sometimes difficult to get a single crystal of sufficient size and quality for traditional single-crystal studies. The solution of a structure can be considered as a three-step process (i) data collection and indexing, (ii) data preparation and Pawley refinement, and (iii) Monte Carlo simulated annealing and rigid-body Rietveld refinement. 

In the recent years, sophisticated modeling tools have become available, such as the Cerius (8), where various modules aUow the analysis of crystallization, crystal growth, and material form characterization. In brief, this technique uses a simulated annealing and a rigid-body Rietveld refinement procedure, whereby the calculated and measured XRPD patterns are compared if they agree sufficiently, the structure is deemed to be solved. Other modules offered by Cerus include ... 

B. C. Chakoumakas, C. J. Rawn, A. J. Rondinone, S. L. Marshall, L. A. Stern, S. Circone, S. H. Kirby, C. Y. Jones, B. H. Toby, and Y. Ishii, The Use of Rigid Body Constraints in Rietveld Refinements of Neutron Diffraction Data of Clathrate Hydrates, in Proc. Fourth Int. Conf. Gas Hydrates, Yokohama 655 (2002). 

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