Hi Tony, > 1) We are refining an organic structure against synchrotron powder data > using TOPAS4. The fitting is pretty good in terms of R factors and > molecular geometry. However, we find that there are some unusual (I > believe, wrong) intermolecular distances in the model. For instance, > O...H-C distance (from O to C) is about 2.9, and O...O distance is about 3 > Ang. Indeed, these distances are not extremely bad. However, according to > the chemical environment, they are not supposed to be so short. In Shelx > (single crystal software), it is easy to restrain such intermolecular > distance, but we do not know how to do it in TOPAS. How do you refine your > structures with restraints in TOPAS or other software?
Chapter 7.10 of the Technical Reference for TOPAS v.4 tell how to use geometry penalty functions during refinements, including, linear distance restraints. Please, familiarize with it . > > 2) The CIF produced by TOPAS is rather brief, which needs a lot of editing > for publication. I wonder what software you use for this purpose? Is there > any publication or book or manual about the best practice of reporting the > CIF from powder data? TOPAS Wiki page is full of useful user-defined macros for various purposes. Please, follow on the link below: http://topas.dur.ac.uk/topaswiki/doku.php?id=macros You need just update your local.inc with one or a set of macro. Hope, it helps. Cheers, Artem
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