I try not to advertise SHELX too often on CCP4bb, but this is just the sort of disorder problem that small molecule crystallographers handle successfully and rather frequently with SHELX. The use of 'free variables' for tying occupancies together and restraining distances to be equal is something that it would be nice to have in phenix or refmac too.
George Prof. George M. Sheldrick FRS Dept. Structural Chemistry, University of Goettingen, Tammannstr. 4, D37077 Goettingen, Germany Tel. +49-551-39-3021 or -3068 Fax. +49-551-39-22582 On Fri, 15 Oct 2010, Jacqueline Vitali wrote: > Dear colleagues, > > I have a tartaric acid on a two fold axis with its two halves related > by the two fold. How do I refine this in Phenix? > > Also I have a SO4 on a 3 fold with S and one O on tthe 3 fold. The > other 3 oxygens are related by the 3-fold. How do I refine this in > phenix? I can put S and one O occupancy 1, what occupancy do I put > for the 3 oxygens that overlap their symmetry mates? > > And how do I maintain stereochemistry around the symmetry axis? These > are not just one atom. For the tartaric acid the 2 fold goes through > the middle of the bond. I could split it in two halves but I do not > see how to keep stereochemistry. > > I would appreciate all suggestions. > > I apologize because the question should go to another newsgroup but I am > still working with my subscription in phenixbb. > > Jackie Vitali >
