Dear Tim, I am sure your statement is too general and is not very precise. 10 deg oscillation range is as precise as 0.1 deg. Positions of diffraction spots on the area detector have defined position on rotation axis within the precision/accuracy of the stepping motor and the spacial resolution of the area detector and NOT defined by oscillation range. If it does, change your setup. We need sometimes 10 deg to have enough reflections for indexing. Obviously we need some reflections to define the orientational matrix and cell dimensions.
FF Dr Felix Frolow Professor of Structural Biology and Biotechnology, Department of Molecular Microbiology and Biotechnology Tel Aviv University 69978, Israel Acta Crystallographica F, co-editor e-mail: [email protected] Tel: ++972-3640-8723 Fax: ++972-3640-9407 Cellular: 0547 459 608 On Mar 25, 2014, at 10:26 , Tim Gruene <[email protected]> wrote: > Dear David, > > I dare claim that rather you do not know how to use the listed programs > in the case for small molecule data rather than none of them were > optimised. E.g. 10degree frames loose all the possible accuracy in the > phi-direction so I am not surprised you had trouble indexing. There is > no reason for that, if you know which parameters to modify. > > In addition to that, concluding from one single data set that programs > are not optimised may be a little overinterpreted. In my experience, > this interpretation does not hold. > > Best, > Tim > > On 03/24/2014 10:03 PM, David Schuller wrote: >> Coincidentally, I just spent my day trying to index a lattice of ~ 10 x >> 10 x 11 A. >> >> Mounting samples: if the compound is stable, just glue it to the end of >> a steel pin. No muss, no fuss. >> >> We had to attenuate our synchrotron beam heavily to make it work; motors >> can only turn so fast. >> >> We did 10 degree rotations to get enough spots per frame per imaging. >> Detector setup allowed for ~ 1 A resolution. >> >> Indexing was a challenge for many of the samples, heavily overloaded >> spots and streaks seemed to be causing the most problems. >> >> We tried various of the usual macromolecular programs for indexing; >> HKL2000, iMosFlm, XDS, DPS. None of them seem to be optimised for this, >> but some of them actually worked in some instances. >> >> >> >> >> >> On 03/24/14 14:04, Andreas Förster wrote: >>> Dear all, >>> >>> I've been approached by a materials student with a petri dish full of >>> big, sturdy, salty, yellow crystals. He claims I have the best kit >>> for single-crystal diffraction on campus. >>> >>> I would very much appreciate advice on how to deal with this, anything >>> in the range from "won't work" to "use software X to analyze data in >>> space group P-43N" would be welcome. >>> >>> Thanks. >>> >>> >>> Andreas >>> >>> >>> >>> >> >> > > -- > Dr Tim Gruene > Institut fuer anorganische Chemie > Tammannstr. 4 > D-37077 Goettingen > > GPG Key ID = A46BEE1A >
