Crystallographic Information Framework

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Index

Core dictionary (coreCIF) version 2.4.5

Category SYMMETRY_EQUIV

Name:
'_symmetry_equiv_[]'

Definition:

   Data items in the SYMMETRY_EQUIV category list the
   symmetry-equivalent positions for the space group.

Examples:

Example 1 - based on data set TOZ of Willis, Beckwith & Tozer [Acta Cryst. (1991), C47, 2276-2277]. 
 
    loop_
    _symmetry_equiv_pos_as_xyz
        +x,+y,+z  1/2-x,-y,1/2+z  1/2+x,1/2-y,-z  -x,1/2+y,1/2-z


Example 2 - based on data set TOZ of Willis, Beckwith & Tozer [Acta Cryst. (1991), C47, 2276-2277]. Formally, the value of _symmetry_equiv_pos_site_id can be any unique character string; it is recommended that it be assigned the sequence number of the list of equivalent positions for compatibility with older files in which it did not appear. 
 
    loop_
    _symmetry_equiv_pos_site_id
    _symmetry_equiv_pos_as_xyz
        1     x,y,z
        2     1/2-x,-y,1/2+z
        3     1/2+x,1/2-y,-z
        4     -x,1/2+y,1/2-z


Type: null

Category: category_overview


International Tables for Crystallography

Volume G: Definition and exchange of crystallographic data

First online edition (2006)

Edited by S. R. Hall and B. McMahon

An essential guide and reference to CIF for programmers, data managers handling crystal-structure information and practising crystallographers.