[ccp4bb] Detwinning

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

Previous message:
Subject: New crystal screening analysis web server...
From: P Hubbard dienoylcoa {- at -} HOTMAIL {- dot -} COM
Date: 2007-04-04

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Subject: Re: bigger size - > better diffraction?
From: artem {- at -} XTALS {- dot -} ORG artem {- at -} XTALS {- dot -} ORG
Date: 2007-04-04

Subject: Detwinning
From: "Sundaramoorthy, Munirathinam" m {- dot -} sundaramoorthy {- at -} VANDERBILT {- dot -} EDU
Date: 2007-04-04

I am working with crystals with apparent I422 space group but it may be actually I4. Twinning analysis shows twinning fraction of 0.46. I tried to detwin the anomalous data in CCP4. Just to check the files were read and written properly, I wrote the detwinned data in ascii. The numbers look strange and needless to say the anomalous Patterson doesn't look good (The Patterson with untwinned data shows single strong site in both I4 and I422, but I couldn't solve the structure in either space group).

There are lot of negative intesities in the output.
0 0 72 -565.57 1621.53 643.51 1700.95
0 0 74 -2454.32 1778.62 3489.49 1845.18
0 0 76 1161.54 1598.13 -657.16 1668.87
0 0 78 1036.44 1492.05 -934.67 1488.42

If I write out Fs, the reflections with negative intensities have 0 for F(+) and value of the previous reflection for F(-).
0 0 72 0.00 0.00 244.28 203.06
0 0 74 0.00 0.00 586.96 153.30
0 0 76 311.74 194.46 586.96 153.30
0 0 78 218.16 192.88 586.96 153.30

Did anyone face a similar problem? I am using version 6.0 of CCP4. The older

Sundar

CCP4bb navigation

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

Previous message:
Subject: New crystal screening analysis web server...
From: P Hubbard dienoylcoa {- at -} HOTMAIL {- dot -} COM
Date: 2007-04-04

Next message:
Subject: Re: bigger size - > better diffraction?
From: artem {- at -} XTALS {- dot -} ORG artem {- at -} XTALS {- dot -} ORG
Date: 2007-04-04