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Modulated and composite structures dictionary (msCIF) version 1.0.1




   This category description does NOT introduce a new category;
   instead, it describes the recommended practice for using
   block codes as described in the core AUDIT_LINK category for
   descriptions of modulated structures.

   The value of _audit_block_code may be associated with a data
   block in the same file or in a different file related to the
   current data block. The value of _audit_block_code should be

   It is recommended that data blocks are named as follows:

           <string>      The name of the data block containing those items that,
                for a particular material, are independent of the
                specific structure (modulated, reference etc.).
                For example, the experimental set-up or
                publication details would be described here.

           <string>_REFRNCE        The name of the data block that contains
               specific details of the reference (unmodulated)
                structure if it was refined separately using only
                main reflections. In the case of composites, this
                data block may contain those items that are common
                to the reference structures of all subsystems.

           <string>_MOD     The name of the data block in which specific
                details of the modulated structure are given. In the
                case of composites, this data block may include
                either those items that are common to the modulated
                structures of all subsystems or the whole modulated
                structure if it is described implicitly through the
                *_subsystem_code pointers.

   A trailing code following the reserved words MOD or REFRNCE
   indicates that the corresponding data block includes
   structural information corresponding to the modulated or
   reference structures of the subsystem labelled by
   _cell_subsystem_code. A recommended format for <string>
   is given in the definitions of _pd_block_[pd] and
   _pd_block_id in the dictionary extension cif_pd.dic


Example 1 - example file for the one-dimensional incommensurately modulated structure of K~2~SeO~4~.
       .               'publication details'
       K2SEO4_COM      'experimental data common to ref./mod. structures'
       K2SEO4_REFRNCE  'reference structure'
       K2SEO4_MOD      'modulated structure'

Example 2 - example with a trailing string referencing a modulated structure of the subsystem labelled by _cell_subsystem_code.
    _audit_link_block_code      'PbSVS2_MOD_VS2'

Type: null

Category: category_overview