Symmetry elements from XYZ
islam
islam at icrf.icnet.uk
Thu Apr 17 05:46:18 EST 1997
I would be grateful for any ideas, comments or software to deal
with the following problem please:
Given an orthogonal dataset of coordinates for 2 identical
molecules is it possible to derive the symmetry operator relating
them or determine if one exists ?
Am I correct in thinking:
* the problem is equivalent to least squares fitting the
two molecules to derive a transformation matrix and then
decomposing/examining the derived matrix to its "simplest
form" e.g. rotation about a 3D axis
* in a sense as long as a transformation matrix can be obtained
to fit one molecule exactly onto another, then a symmetry op
always exists defined by the matrix ?
Can the above idea be extended to derive the crystallographic
symmetry operator relating the two molecules (obviously given
the appropriate cell,space group etc). (An alternative here,
I guess, would be to generate unit cells to find which symmetry
elements related to the 2 molecules).
Thanks.
____________________________________________
Suhail A Islam
Biomolecular Modelling Laboratory
Imperial Cancer Research Fund, P.O. Box 123
44 Lincoln's Inn Fields, London WC2A 3PX
Tel: (0171) 269 3380, Fax: (0171) 269 3479
email: islam at icrf.icnet.uk
http://www.icnet.uk/bmm/
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