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Crystals User GuideChapter 6: RegularisationAs explained above (Part 4), Fourier techniques provide a powerful way
for initiating the refinement of a structure. When the geometry of fragments
are well known from previous analyses, for example phenyl groups, the initial
refinement can be speeded even futher by forcing the observed fragment to
adopt an idealised geometry. This process, common in protein crystallography,
is known as regularisation, and can be used not only to tidy up a poor
geometry, but also to postulate sites for missing atoms.
[Top] [Index] Manuals generated on Wednesday 8 November 2006 6.1: EXAMPLE 1Regularising a cyclopentadienyl ring. The idealised coordinates are from the literature. \REGULARISE REPLACE GROUP 5 OLD C(1) C(2) C(3) C(4) C(5) ATOM 0 0 0 ATOM .846 1.165 0 ATOM .846 -1.165 0 ATOM 2.216 0.72 0 ATOM 2.216 -0.72 0
Completing and regularising a phenyl ring. C(3) is very poorly placed, and so will first be deleted, and C(6) has not been found at all. New atoms will be generated for them. \EDIT DELETE C(3) \REGULARISE REPLACE OLD C(1) C(2) C(3) C(4) C(5) C(6) PHENYL END
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© Copyright Chemical Crystallography Laboratory, Oxford, 2006.
Comments or queries to David Watkin -
david.watkin@chem.ox.ac.uk Telephone +44 1865 285019.
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