[phenixbb] ncs restraints weight
Pavel Afonine
PAfonine at lbl.gov
Mon Aug 6 10:31:10 PDT 2007
Hi,
yes, this is correct: phenix.refine offers NCS restraints only. Here are
two parameters you may want to play with:
ncs
{
coordinate_sigma=None
b_factor_weight=None
}
This will set up specified values for all NCS groups. Try an array of
values to see which value works best (monitoring Rfree and overall
stereochemistry). The defaults are 0.05 and 10, for coordinates and ADP
correspondingly. Making coordinate_sigma smaller makes the NCS
restraints tighter.
Alternatively, you can set set different values for each NCS group like
in example below:
ncs
{
restraint_group {
reference=XXX
selection=YYY
coordinate_sigma=0.05
b_factor_weight=10
}
restraint_group {
reference=AAA
selection=BBB
coordinate_sigma=0.03
b_factor_weight=5
}
restraint_group {
reference=ZZZ
selection=QQQ
coordinate_sigma=0.01
b_factor_weight=2
}
}
Be careful to not deviate too much from the default
coordinate_sigma=0.05 since it may results in overall stereochemistry
distortion. Anyway, like I said above, try an array of values and see
which works best (judging by Rfree and overall geometry).
Please let me know if you have more questions.
Pavel.
Daniele de Sanctis wrote:
> Dear all,
>
> i'm refining a low resolution structure (3.2A) with four molecules in
> the asymmetric unit. I saw that phenix.refine doesn't allow
> constraints, so i'd like to change the restraints weight but i can't
> find the right keyword...
>
> thanks for your help
>
> d
>
>
More information about the phenixbb
mailing list