[phenixbb] refinement with anomalous data

Pavel Afonine pafonine at lbl.gov
Fri Feb 6 11:29:43 PST 2015

If data set isn't anomalous then I don't see why you would want to 
refine against I+/I-.

On 2/6/15 11:26 AM, Guangyu Zhu wrote:
> What I meant is: I actually don’t have anomalous signal, so when I use 
> I+/I-, kind of like I use Imean twice for each reflection. Can I do 
> that?  My guess is that the resolution is low, so double 
> reflection/parameter ratio really benefits the refinement, although 
> overall the weight for x-ray term is not change, because rms bond and 
> angle are similar.
> Newer versions are better for my other refinement with higher 
> resolution, but not this data set.
> Guangyu
> From: Pavel Afonine <pafonine at lbl.gov <mailto:pafonine at lbl.gov>>
> Date: Friday, February 6, 2015 at 2:12 PM
> To: Guangyu Zhu <gzhu at hwi.buffalo.edu <mailto:gzhu at hwi.buffalo.edu>>, 
> "phenixbb at phenix-online.org <mailto:phenixbb at phenix-online.org>" 
> <phenixbb at phenix-online.org <mailto:phenixbb at phenix-online.org>>
> Subject: Re: [phenixbb] refinement with anomalous data
>> I use same data set for refinement, so Rfree is also marked for same 
>> reflection. The only difference is that I chose “Data labels” from 
>> Phenix IMEAN or I(+) I(-).
> What I meant is that the IMEAN set is not the same as I(+),I(-) at 
> least because the number of reflections in IMEAN is not the same as in 
> I(+),I(-).
>> By the way, I use version 1.8.2 for refinement. Newer versions gives 
>> higher R/Rfree.
> Should be the other way around...
> Pavel

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