Re: [ccp4bb] anisotropic diffraction in refinement

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: cracking crystal
From: Leonard Thomas lmthomas {- at -} OU {- dot -} EDU
Date: 2009-09-01

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Subject: Re: cracking crystal
From: Jim Pflugrath Jim {- dot -} Pflugrath {- at -} RIGAKU {- dot -} COM
Date: 2009-09-01

Subject: Re: anisotropic diffraction in refinement
From: Pavel Afonine PAfonine {- at -} LBL {- dot -} GOV
Date: 2009-09-01

Hi Justin,

may be I mis-understood your question, but can't anisotropic scale
factor that is the part of the total structure factor (as defined in
phenix.refine for example and most likely in the other programs):

Fmodel = scale_overall * exp(-h*U_overall*ht) * (Fcalc_atoms + k_sol *
exp(-B_sol*s^2) * Fmask)

take care of this (S. Sheriff & W.A. Hendrickson. Acta Cryst. (1987).
A43, 118-121. "Description of overall anisotropy in diffraction from
macromolecular crystals")?

For an example of how important to use anisotropic scale for anisotropy
correction, see slide #20 here:
http://phenix-online.org/presentations/neutron_japan_2009/phenix_japan_part1.pdf

Pavel.

On 9/1/09 7:35 AM, Justin Hall wrote:
> Dear All;
>
> I am working with a data set which is anisotropic. The resolution
> limits are ~ 2.75 by 3.45 A. The I have integrated (using Mosflm) the
> data out to 2.75 A, the data therefore includes a mix of real (I/sig
> >>1) and imaginary (I/sig ~1) data past the 3.45 A resolution bin.
>
> I am concerned that the presence of the poor quality data in the outer
> shells will cause my good data to 2.75 A resolution to be down
> weighted in refinement. Since anisotropic resolution limits do not
> seem to be an option, are there other tools that would allow proper
> weighting for this situation?
>
> Cheers~
>
> ~Justin Hall
> Oregon State University

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: cracking crystal
From: Leonard Thomas lmthomas {- at -} OU {- dot -} EDU
Date: 2009-09-01

Next message:
Subject: Re: cracking crystal
From: Jim Pflugrath Jim {- dot -} Pflugrath {- at -} RIGAKU {- dot -} COM
Date: 2009-09-01