Dear CCP4ers,
does any of you have a good reference describing the symmetry of
crystallographic stereographic projections? There is a lot of
literature describing rotational symmetry in Eulerian angular space,
but I'm not aware of any for polar angles. In particular, I've
calculated a self-rotation function for a crystal in space group C2
with a monoclinic beta-angle of 97 degrees in a convention where Phi
is the angle from the x-axis (=a-axis) and Psi is the angle from the
monoclinic b-axis. I get a beautiful peak for a seven-fold rotation
axis at Phi=83 degrees and Psi=90 degrees. I think that the seven-
fold NCS-axis should point along the crystallographic c-axis, but
then I would expect Phi=97 and Psi=90. Presumably, there must be a
symmetry with the term Phi' = 180-Phi, but I would like to _know_ it.
I would be grateful for any pointer to a good reference describing
symmetry in crystallographic stereographic projections, also for
future cases.
Best regards,
Dirk.
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Dirk Kostrewa
Gene Center, A 5.07
Ludwig-Maximilians-University
Feodor-Lynen-Str. 25
81377 Munich
Germany
Phone: +49-89-2180-76845
Fax: +49-89-2180-76999
E-mail: [EMAIL PROTECTED]
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