Full details here: Pubmed ID: 20057079
As Ian says, sometimes the spot splitting was particularly visible, sometimes it was not. SAINT was not able to integrate the split spots separately (it works great for non-merohedral twins though, followed by TWINABS for scaling). In the end, I ended up using XDS and even the most severely split spots were nicely integrated in the same integration box. Putting the pseudo-merohedral twin operator in to SHELXL dropped R/R-free and improved the GooF and least-squares refinement convergence, even though the twin fraction was rather low (~ 5%).
HTH, Jonathan -- Jonathan Elegheert Ph.D. Student Unit for Structural Biology& Biophysics http://www.lprobe.ugent.be/xray.html Lab for Protein Biochemistry and Biomolecular Engineering Department of Biochemistry& Microbiology Ghent University, Belgium e-mail: jonathan.eleghe...@ugent.be Op 6/23/2010 11:46 AM, Frank von Delft schreef:
Both DIRAX or SAINT should be able to handle it, you'll need SADABS to scale it. (The latter two are in the Bruker software.)My experience with pseudo-merohedral twinning (it was actually the reticular case with half the spots overlapped and the other non-overlapped half on a pseudo C-centred lattice) is that the degree of splitting varies widely over the diffraction pattern. In some places there was complete overlap, in others you see elongation of the spots, in others partial separation, and in others complete separation (and of course all shades in-between), with around 50-50 intensity split. In this situation the mosaicity becomes meaningless! I'm not aware of any software that can handle this kind of thing successfully (and certainly the data we did manage to get turned out to be garbage!).phx.
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