International
Tables for
Crystallography
Volume G
Definition and exchange of crystallographic data
Edited by S. R. Hall and B. McMahon

International Tables for Crystallography (2006). Vol. G. ch. 3.4, p. 134

Section 3.4.3.2. Analysis

G. Madariagaa*

aDepartamento de Física de la Materia Condensada, Facultad de Ciencia y Tecnología, Universidad del País Vasco, Apartado 644, 48080 Bilbao, Spain
Correspondence e-mail: gotzon.madariaga@ehu.es

3.4.3.2. Analysis

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The categories related to refinement that have been extended in this dictionary are as follows:

Refinement techniques and results (§3.4.3.2.1[link])
REFINE
The reflections used in the refinement (§3.4.3.2.2[link])
REFLN
REFLNS

Categories marked with ¶ are already defined in the core CIF dictionary.

3.4.3.2.1. Refinement techniques and results

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New data items in this category are as follows:

REFINE [Scheme scheme12]

During the early stages of the development of the msCIF dictionary, several sets of data items were defined to accommodate the need to specify residual R factors for the different sets of main reflections and satellite reflections. It was then recognized that the binning of reflection classes had more general application, and these new data items were transferred to the core CIF dictionary, where, of course, they are still available for use in an msCIF.

The new items in the REFINE category in the msCIF dictionary are specific to the refinement of modulated structures. _refine_ls_mod_func_description allows a free-text description of the types of modulation present in the structural model and how they are handled. The treatment of hydrogen-atom modulation parameters is specified by _refine_ls_mod_hydrogen_treatment. Information on an overall phason correction (the use of which should in general be discouraged) may be given using the _refine_ls_mod_overall_phason_* items.

3.4.3.2.2. The reflections used in the refinement

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New data items in these categories are as follows:

(a) REFLN [Scheme scheme13]

(b) REFLNS [Scheme scheme14]

As with the _diffrn_refln_* and _diffrn_reflns_* items (Section 3.4.3.1.2[link]), these data names extend the corresponding core data items into the higher-dimensional space used in the treatment of modulated structures and composites. They apply to the list of reflections used in the refinement, as distinct from the experimentally collected set of intensities described by the _diffrn_* data items.








































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