[phenixbb] Twin refinement with anomalous pairs

Peter Zwart PHZwart at lbl.gov
Mon Oct 20 22:13:54 PDT 2008


Hi,

When anomalous data is available, both F+ and F- will be assumed to be
independent variables (unless you merge them as Pavel described). I
did refine f' and f" for a nice high reso twinned data set once and
the results were quite encouraging. I am not sure how reliable this
would be for more challenging data.

HTH

Peter





2008/10/20, Pavel Afonine <PAfonine at lbl.gov>:
>
>  Hi Francis,
>
>  by default both F+ and F- are used in phenix.refine. However, you can
> request that the average values, Fobs_ave = (F+ + F-)/2 are used instead
> ("xray_data.force_anomalous_flag_to_be_equal_to=False"
> keyword).
>
>  Peter may have more details on how this is handled in twin-refinement.
>
>  Pavel.
>
>
>
>  On 10/20/2008 7:45 AM, Francis E Reyes wrote:
> All
>
>
> How does phenix.refine handle the twin refinement target when refining
> against F+/F-?  I'm specifically asking for the proper assignment of F+/F-
> for twin related reflections (e.g.
> 10.1107/S0907444902021704).  My data is currently in P41
> with friedel pairs as output by scala.
>
>
>
>
> Thanks
>
>
> FR
>
>
>
>
>
> ---------------------------------------------
>  Francis Reyes M.Sc.
>  215 UCB
>  University of Colorado at Boulder
>
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>
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