Dear All, first of all, I would like to thank the many good people who have responded to my query. Yet another truly interesting discussion on this BB!
As a partial summary, two points: 1. Few people suggested that our high Rmerge problem could be caused by experimental troubles like phi angle imprecision rather than the crystal itself. Thus far we could not find indications for that but maybe we did not look carefully enough. However, the frames ARE weak, and I tend to think that this is the main cause of the problem. 2. Few people argued that data processing programs (XDS in particular) 'should' handle thin frames as efficiently as thicker frames... After digesting these (very useful!) arguments, I still tend to think that the best proof would be in the pudding, i.e. trying to pool thin frames into thicker frames (but I do not have an immediate means of doing this... ) Sergei
Dear All, I am processing a dataset collected (not by me) with 0.1 degree oscillations. The diffraction is quite weak even though there is a clean diffraction pattern to about 3A. Either Mosflm or XDS processes the data readily with +/- default settings but both yield a high overall Rmerge of about 0.23 in the expected symmetry. Processing in P1 yields an overall Rmerge of ~0.18, but what is especially disappointing is that Rmerge is as high as 0.15 at ~5A resolution already. The question is, how can we process the data so that the merging statistics becomes more reasonable? Apparent mosaicity turns out to be ~0.5A. My naive way of thinking is to try treating each five consecutive frames as a single 0.5 degree frame. Does anyone have experience with this? Many thanks in advance, Sergei
-- Prof. Sergei V. Strelkov Laboratory for Biocrystallography Department of Pharmaceutical Sciences, Katholieke Universiteit Leuven O&N2, Campus Gasthuisberg, Herestraat 49 bus 822, 3000 Leuven, Belgium Work phone: +32 16 330845 Fax: +32 16 323469 OR +32 16 323460 Mobile: +32 486 294132 Lab pages: http://pharm.kuleuven.be/anafar
