On Thursday, 23 July 2015 12:04:34 AM Keller, Jacob wrote:
> Dear Refmac developers et al,
>
> I read in a recent paper (ref on request):
>
> "REFMAC5 internally changes free R flags so that twin-related reflections belong
> to the either the free or the working set."
>
> Can someone from the team assure me that this is indeed true?
> But if it's true, doesn't it also compromise the sanctity of the work/free sets?
If you have twinned data then your Rfree set is already compromised,
because pairs of reflections related by the twin law contribute to
each other's measured intensity. The operation described is an
obvious way to recover from this state.
If you cleverly selected your Rfree set using some algorithm that
always assigns the twin-law pairs in same Rfree status then this
operation is not necessary, but also it has no effect since the
condition it tests for is already true.
Ethan
> I thought that changing freeR flags defeats the purpose of having a free set. I would love to hear a good argument otherwise, though, or how the specific procedure implemented in Refmac avoids this problem.
>
> JPK
--
mail: Biomolecular Structure Center, K-428 Health Sciences Bldg
MS 357742, University of Washington, Seattle 98195-7742
|