[phenixbb] twinning question

Paul Adams pdadams at lbl.gov
Fri Apr 20 07:26:14 PDT 2012


The effects of twinning on the intensity distributions should be seen in even the highest point group. However, there won't be twin laws to test for twinning (and hence twin fraction estimation). For a more complete analysis looking at the data processed in the lower symmetry (P6 or below) would be better.

On Apr 20, 2012, at 8:42 AM, wtempel wrote:

> Did I infer correctly from Padilla & Yeates (2002) Acta Cryst D59:1124-30 that the L-test could indicate twinning even if data were merged in the apparent higher-symmetry point group?
> Wolfram Tempel
> 
> On Thu, Apr 19, 2012 at 12:45 PM, Patrick Loll <pat.loll at drexel.edu> wrote:
> Dumb question here: When one runs the various twinning tests (e.g. phenix.xtriage), is one meant to use data processed in the higher symmetry SG, or the lower symmetry SG?
> 
> A concrete example: I can process a data set in a 622 point group w/ reasonable merging statistics, but an abnormally low solvent content raises my suspicions. So do I process as P6, and submit these data to the twinning test? Or do I submit the data processed as P622?
> 
> Pat
> 
> ---------------------------------------------------------------------------------------
> Patrick J. Loll, Ph. D.
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Paul Adams
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