Re: [ccp4bb] pointless (1.2.0) and enantiomorphic SG's

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

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Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Martyn Winn m {- dot -} d {- dot -} winn {- at -} DL {- dot -} AC {- dot -} UK
Date: 2007-11-09

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Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Kevin Cowtan cowtan {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-11-09

Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: "Winter, G (Graeme)" g {- dot -} winter {- at -} DL {- dot -} AC {- dot -} UK
Date: 2007-11-09

I recall that this has been discussed, more than once, on the ccp4-dev
board and quite sensible solutions provided to this, for instance the
inclusion of a one-character flag which would indicate the level of
correctness of the spacegroup information - along the lines of

L => Bravais lattice correct
P => pointgroup correct
E => spacegroup or enantiomorph
S => spacegroup is correct

I can't find the appropriate email as it is buried in the mists of time,
so the particular characters here may be different to those proposed.
However, the idea was a sound one.

This would need to go into the CCP4 MTZ library of course... And would
be a very valuable addition.

Cheers,

Graeme

-----Original Message-----
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of
Phil Evans
Sent: 09 November 2007 13:54
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] pointless (1.2.0) and enantiomorphic SG's

I agree

On 9 Nov 2007, at 13:50, Eleanor Dodson wrote:

> As I often say!!! The mtz format should carry point group and
> alternate SGs - then be upgraded when youknow the correct SG..
>
> Eleanor
>
> Phil Evans wrote:
>> It just picks the first in the list, to store in the output MTZ file,

>> which can only handle one (92 < 96) Phil
>>
>>
>> On 8 Nov 2007, at 22:26, Bryan W. Lepore wrote:
>>
>>> when pointless (1.2.0) finds enantiomorphic SG's, what is the
>>> criterion for 'Selecting' one over the other?
>>>
>>> e.g. i ran pointless on some tetragonal data, and the enantiomorphs
>>> SG92/SG96 are selected as strong candidates
>>>
>>> Spacegroup TotProb SysAbsProb Reindex
>>> Conditions
>>>

( 92) 0.956 0.956 00l:
>>> l=4n, h00: h=2n (zones 1,2)
>>>

( 96) 0.956 0.956 00l:
>>> l=4n, h00: h=2n (zones 1,2)
>>>
>>> ... then pointless reports :
>>>
>>> Selecting space group P 41 21 2 as solutions are enantiomorphic
>>> Best Solution space group P 41 21 2
>>>
>>> ... is that b/c pointless can only report one, and SG92 came up
>>> first?
>>>
>>> -bryan
>>
>>
>

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

Previous message:
Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Martyn Winn m {- dot -} d {- dot -} winn {- at -} DL {- dot -} AC {- dot -} UK
Date: 2007-11-09

Next message:
Subject: Re: pointless (1.2.0) and enantiomorphic SG's
From: Kevin Cowtan cowtan {- at -} YSBL {- dot -} YORK {- dot -} AC {- dot -} UK
Date: 2007-11-09