For people using bond-restraints on medium to large inorganic/zeolite structures to keep things physically reasonable during Rietveld refinement (for data of moderate quality): are there any comments on how R-factors tend to vary if restraints are released - or set to near zero values. Are there negligible drops in R-factors as atoms start wandering away on a holiday in unrestrained refinements vs restrained refinements? (this assumes the model is basically correct) It would be interesting to hear also on this topic for organics if people have the time. Thanks in advance, Lachlan. ----------------------- Lachlan M. D. Cranswick Geochemistry - Lamont-Doherty Earth Observatory, Columbia University PO Box 1000, 61 Route 9W Palisades, New York 10964-1000 USA Tel: (845) 365-8662 Fax: (845) 365-8155 E-mail: [EMAIL PROTECTED] WWW: http://www.ldeo.columbia.edu CCP14 Xtal Software Website: http://www.ccp14.ac.uk