Re: [ccp4bb] twinned?

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From: Bart Hazes bart {- dot -} hazes {- at -} UALBERTA {- dot -} CA
Date: 2008-04-03

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Subject: Re: twinned?
From: Lijun Liu liulj {- at -} UOXRAY {- dot -} UOREGON {- dot -} EDU
Date: 2008-04-03

If the space group is correct, it sounds to me this is strange
statistics
away from both an ideal untwined and a perfect twinned structure.

I do suggested the data should be checked if the I-->F was completed.
If used I as F, these two values sound reasonable.

> <
I
^2>/(<
I
>)^2 = 3.2236 (2.0 for untwinned, 1.5 for twinned)
> (<
F
>)^2/<
F
^2> = 0.6937 (0.785 for untwinned, 0.865 for twinned)

On Apr 2, 2008, at 8:33 AM, Qiang Chen wrote:

> Hi all,
>
> The data I am working on has a strong translation vector. The space
> group
> is C2221 and resolution is 2.3 angstrom. There are two molecules
> per AU
> with a pseudo-2-fold axis.
> On the cumulative intensity distribution plot, the theor and obser
> curves
> totally do not overlap. I did "detect_twinning" from CNS, and there
> is the
> result:
>
> <
I
^2>/(<
I
>)^2 = 3.2236 (2.0 for untwinned, 1.5 for twinned)
> (<
F
>)^2/<
F
^2> = 0.6937 (0.785 for untwinned, 0.865 for twinned)
> Does the result mean my data is not twinned?
>
> Any suggestion will be highly appreciated.
> Thank you!
>
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Lijun Liu, PhD
Institute of Molecular Biology
HHMI & Department of Physics
University of Oregon
Eugene, OR 97403
541-346-4080

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CCP4bb <-- 2008 <-- April 2008 <-- 03 April 2008

Previous message:
Subject: Re: twinned?
From: Bart Hazes bart {- dot -} hazes {- at -} UALBERTA {- dot -} CA
Date: 2008-04-03

Next message:
Subject: Your opinion about the attached diffraction pattern
From: Ibrahim Moustafa I {- dot -} moustafa {- at -} PSU {- dot -} EDU
Date: 2008-04-03