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Re: [ccp4bb] Can't choose full H-M symbol for conventional cell ?

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
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Subject: Re: Can't choose full H-M symbol for conventional cell ?
From: Jim Pflugrath jim {- dot -} pflugrath {- at -} RIGAKU {- dot -} COM
Date: 2007-03-18
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Subject: questions related to refmac refinement and map-fitting
From: lithomas lithomas {- at -} DRAGON {- dot -} NCHU {- dot -} EDU {- dot -} TW
Date: 2007-03-19


Subject: Re: Can't choose full H-M symbol for conventional cell ?
From: Petrus H Zwart PHZwart {- at -} LBL {- dot -} GOV
Date: 2007-03-18

> > For example for space group no 18 with the 'short' H-M symbol 'P 2/1 2/1
> > 2' in the setting with 'full' H-M symbol 'P 2 2/1 2/1' the programs
> > choose the correct conventional cell as say a=60, b=70, c=90
> > (according to the convention a<=b<=c).

The convention is aIf you have
(60 70 80 90 90 90) P 2 21 21
I think the reference setting (using cctbx/sginfo terminology) you are looking for is

(70 80 60 90 90 90) P 21 21 2.

If you have data in any weerd setting, using

iotbx.reflection_file_converter mydata.sca --change_basis=to_reference_setting --sca=reindexed.sca

should get you back to the reference setting.

Not sure about ccp4 programs, but programs based on the cctbx symmetry libraries, should be able to handle data in unusual settings, which is usefull in some situtaions.

HTH

Peter






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