Hi Tim,
If you start from nearly identical copies (due to previous refinement), in the absence of a strong signal from the data, it is expected that the copies remain fairly similar even if you increase the sigma / lower the weight. We just added a new feature to phenix.refine that could be useful to introduce differences between the NCS copies, guided by the model density through a new real-space refinement protocol: strategy=individual_sites_real_space plus real_space_refinement.mode=lockit. At your resolution it is turned on by default. I.e. to try it out all you need to do is get dev-602 or higher and run phenix.refine again. Only trouble, those installers aren't generally visible since there were some minor problems, but watch out for a new one soon.
Ralf
From: Timothy Springer <[email protected]>
To: [email protected]
Sent: Tue, December 7, 2010 7:31:44 PM
Subject: [phenixbb] ncs restraints
Hi, I am using NCS restraints for 4 copies of a molecule at 3.05 �. We are using the standard weights:
coordinate_sigma = 0.05
b_factor_weight = 10
and the 4 molecules look identical. What are suggested values for looser restraints? One of my colleagues said that varying them did not make a difference- ncs was still very strict. Is there a way to make them less strict?
Thanks,
Timothy A. Springer, Ph.D.