Draft CIF dictionary for rgid body description

[David Brown]

Dear Colleagues,

In January I circulated to you, the coreCIF Dictionary Maintenance 
Group, the draft of a CIF dictionary containing items for reporting the 
restraints and constraints that were applied during the final round of 
refinement.  This was approved by this group after a six week 
consultaion period and passed on to COMCIFS for final approval.  During 
this stage an objection was raised that under the proposal it was not 
possible for an atom to belong to more than one rigid body, because the 
rigid bodies were defined by a flag in the atom_site list which 
identified which rigid body a partcular atom belonged to. 

In order to address this weakness, Ilia Guzei and I have proposed an 
amendment to the earlier draft.  This is more flexible in that it 
defines each rigid body in terms of any atom in the atom_site list 
together with a symmetry operation.  This places no restriction on the 
number of rigid bodies an atom can belong to.  I am circulating this 
amendment in the attached ASCII file which contains the amended 
dictionary text.

Can you please check this and respond to this Discussion List with your 
approval or reservation before September 10 (2010-09-10).  If there are 
no unresolved issues at that time, I will incorporate this amendment 
into the original restraint dictionary and pass it back to COMCIFS for 
final approval.

I am looking forward to heariing from you

David Brown
Chair CoreCIF DMG

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://scripts.iucr.org/pipermail/coredmg/attachments/20100811/6c0ab779/attachment.html 
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: RestraintsChanges100811.dic
Url: http://scripts.iucr.org/pipermail/coredmg/attachments/20100811/6c0ab779/attachment.ksh 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: idbrown.vcf
Type: text/x-vcard
Size: 298 bytes
Desc: not available
Url : http://scripts.iucr.org/pipermail/coredmg/attachments/20100811/6c0ab779/attachment.vcf