Dear Felix,
as far as I understand we are talking about the frame width, not the
total data range for indexing ("10 degree rotations to get enough spots
per frame"). I have used 180degrees of data for indexing. At least XDS
places the reflection at the centre of the frame so that with a 10deg
frame width the position is know within +/-5 degree - it is not
surprising indexing fails here.Regards, Tim On 03/25/2014 09:41 AM, Felix Frolow wrote: > 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: mbfro...@post.tau.ac.il > Tel: ++972-3640-8723 > Fax: ++972-3640-9407 > Cellular: 0547 459 608 > > On Mar 25, 2014, at 10:26 , Tim Gruene <t...@shelx.uni-ac.gwdg.de> 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 >> > > -- Dr Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A
signature.asc
Description: OpenPGP digital signature
