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Re: Transfer from msCIF: refine_ls_class category

  • To: Multiple recipients of list <coredmg@iucr.org>
  • Subject: Re: Transfer from msCIF: refine_ls_class category
  • From: Howard Flack <Howard.Flack@cryst.unige.ch>
  • Date: Tue, 4 Aug 1998 20:08:12 +0100 (BST)
> 
> David has also suggested that the REFINE_LS_CLASS category in the modulated
> structures dictionary should be moved lock, stock and barrel to the core:

  In principle I agree. This will save duplication of names.
  In practice the text needs amending to allow for "ordinary" space
groups and structures. =>

> ;
>     loop_
>         _refine_ls_class_R_factor_gt
>         _refine_ls_class_code
>                 0.057    'Main'
>                 0.074    'Com'
>                 0.064    'NbRefls'
>                 0.046    'LaRefls'
>                 0.112    'Sat1'
>                 0.177    'Sat2'
> ;
> ;
>     Example 1 - extracted from van Smaalen [(1991). J. Phys.:Condens. Matter 3, 
>                 1247-1263.]
> ;

     Example 0 might have a set of R factors in terms of parity "groups"
of reflections.


> # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
>       _definition
> ;              Data items in the REFINE_LS_CLASS category record details 
>                (for each reflection class separately) about the reflections used
>                for the structure refinement. Each reflection class is normally 
>                defined by the number m=sum|mi|, where the mi are the integer 
>                coefficients that, in addition to h,k,l, index the corresponding 
>                diffraction vector in the basis defined in 
>                _cell_reciprocal_basis. However reflection classes 
>                could be defined, if convenient, in a more general and flexible
>                way.
> ;

  What is called the "normal" definition in the above is not really
meaningful for "normal" space groups and structures.

H.

 
-- 
Howard Flack        http://www.unige.ch/crystal/ahdf/Howard.Flack.html
Laboratoire de Cristallographie               Phone: 41 (22) 702 62 49
24 quai Ernest-Ansermet             mailto:Howard.Flack@cryst.unige.ch
CH-1211 Geneva 4, Switzerland                   Fax: 41 (22) 781 21 92

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