[phenixbb] 0 for wxc_scale and wxu_scale?

Frank von Delft frank.vondelft at sgc.ox.ac.uk
Wed Nov 26 15:34:26 PST 2008

>> I am refining a structure with a resolution of 2.1 Angstroem using Phenix.
>> The spacegroup is P 31 2 1 (No. 152) with a twin fraction of 0.37 and twin 
>> law -h,-k,l.
>> In the refinement procedure the NCS (4 chains) constraints are on, using 
>> individual sites, ADP and occupancy refinement.
> Just a suggestion to quickly try out... What happens if you turn off the 
> NCS restraints and do some refinement without using NCS (with and/or 
> without optimizing the weights)? I know it depends on many factors, but 
> I've seen a good number of cases at around 2A resolution where the 
> refinement was better if NCS is not used.
I can't not respond:  I've never had a case where *careful* evaluation 
and assignment of NCS groups did /not/ allow me to tighten NCS 
restraints (without screwing Rfree, of course).  But of course, it 
requires work:  the default procedures aren't good enough yet.


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