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Re: coreCIF.dic-2.4 Discussion List #8

  • To: Distribution list of the IUCr COMCIFS Core Dictionary Maintenance Group <coredmg@iucr.org>
  • Subject: Re: coreCIF.dic-2.4 Discussion List #8
  • From: "George M. Sheldrick" <gsheldr@shelx.uni-ac.gwdg.de>
  • Date: Thu, 29 Jun 2006 12:28:46 +0200
  • In-Reply-To: <44A0F750.6090303@flack.ch>
  • Organization: Dept. Structural Chemistry, Goettingen University
  • References: <444921A5.8060409@mcmaster.ca> <44A0F750.6090303@flack.ch>
My term doesn't finish until July 21st, but since restraints and 
constraints have come up again I cannot resist commenting. The main 
reason why it is not possible to reproduce a crystal structure 
refinement from the data in CIF file is that most of the information 
about the restraints and constraints that were applied in the refinement 
has been lost or degraded. It is no secret that the majority of small 
molecule structures are refined with a program called SHELX. The last 
time a change was made to the definitions of the restraints and 
constraints used by that program was 1993. In fact many of them date 
back to the 1976 version. Surely we have had enough time to find a way 
of incorporating this information properly into a CIF file? Otherwise I 
may feel obliged in the next version of SHELX (if there is one) to embed 
the .res file - which contains all this information in a concise and 
unambiguous form - into the CIF file, as many users have requested.


Howard Flack wrote:
> Term has finished.

Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-3021 or -3068
Fax. +49-551-39-2582

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