Low completeness with twinned data

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trrk
Sealed Tube
Posts: 25
Joined: 31 Aug 2011, 09:17

Low completeness with twinned data

Post by trrk » 30 May 2017, 15:58

I have a data set which I have processed normally as a single crystal and separately as a twin. The twinned refinment against the hklf5 (with BASF of ~0.2) is slightly better than the single one except that the data is only 83% complete rather than 99% when refined as a single crystal. Of course this gives an A alert in Cifcheck. Does anyone know the reason for this and whether there is any way to fix it or to adjust data collection in the future to avoid this? I am tempted just to use the single refinement as the R factor is only ~1% higher than the twin refinement - do you think this is acceptable? The data was collected and processed with Apex3.

wlewis
Rotating Anode With Optics
Posts: 186
Joined: 23 Apr 2009, 19:48
Location: University of Nottingham

Re: Low completeness with twinned data

Post by wlewis » 31 May 2017, 11:09

In the twin handling there will be an overlap rejection somewhere I think. There should be a threshold to set at which point partially overlapped reflections will be rejected.

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