ISSN:
1600-5724
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
An algorithm is given which is suitable for solving molecular structures when the shape of the whole molecular skeleton, or at least the main part of it, can be assumed. The molecular parameters, i.e. three rotations and three translations in the general case, are randomly generated by a Monte-–Carlo method. The packing thus obtained is group-refined using only a few selected strong reflexions, then kept or rejected according to several tests on the weighted reliability index; the best structures are furtherly group-refined using an increasing number of reflexions up to a given limit. The whole program has been arranged to be as fast as possible and fully automatic. Such a method is helpful when the experimental data are poor or restricted to some extent (high-pressure single-crystal data, unstable crystals .... ) or in cases of static or dynamic disorder (plastic crystals). Even when accurate three-dimensional data are available, it may be of value and possibly faster than other methods, if one or several molecular parameters are a priori fixed from symmetry considerations or one atom located (heavy atom). Several typical examples of structures which have been solved or redetermined are given.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0567739472001184
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