Re: [ccp4bb] Rfree statistics in SHELXL

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

Previous message:
Subject: Rfree statistics in SHELXL
From: Oliv Eidam eidamo {- at -} BIOC {- dot -} UNIZH {- dot -} CH
Date: 2007-10-08

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Subject: Re: Rfree statistics in SHELXL
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2007-10-08

Subject: Re: Rfree statistics in SHELXL
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2007-10-08

SHELX is much older than the free R so this was added as an afterthought,
and unfortunately I did not think of calculating R-free for just the outer
resolution shell. There isn't an easy way of doing this without some
programmeing effort. I also think that it is NOT a good idea, in the outer
resolution shell you may only about 100 reflections in your free R set, so
the free R value will have a very large esd and so could be misleading.

George

Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-3021 or -3068
Fax. +49-551-39-2582

On Mon, 8 Oct 2007, Oliv Eidam wrote:

> Dear all,
>
> I used SHELXL for anisotropic structure refinement of high-resolution data
> (1.3 Angstroem) and a reviewer asked me to include refinement statistics for
> the outer most resolution shell in the crystallographic table. While R-factors
> for the outer most resolution shell belong to the standard output in REFMAC or
> CNS, it seems to me that SHELXL calculates R-factors only for reflections of
> the work set. I also noticed that test reflections are missing in the
> structure factor file (.fcf file) generated by shelxpro, preventing me to use
> the [S] or [L] options in shelxpro to calculate R(free) statistics.
> Is it simply not possible to calculate the R(free) factor for the outer most
> shell after SHELX refinement? Or is there a problem with my SHELX program?
>
> Many thanks for your answers and suggestions,
>
> Oliv
>
>
> --
> Oliv Eidam
>
> Department of Biochemistry
> University of Zurich
> Winterthurerstrasse 190
> 8057 Zurich, Switzerland
>
> Phone: 0041-44-635-6563
> Email: eidamo@bioc.uzh.ch
> Web: http://www.bioc.uzh.ch/gruetter
> NCCR: http://www.structuralbiology.ethz.ch
>
>

CCP4bb navigation

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

Previous message:
Subject: Rfree statistics in SHELXL
From: Oliv Eidam eidamo {- at -} BIOC {- dot -} UNIZH {- dot -} CH
Date: 2007-10-08

Next message:
Subject: Re: Rfree statistics in SHELXL
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2007-10-08