Restraints dictionary version 1.0

Category RESTR_PARAMETER_CLASS

Name:
'_restr_parameter_class_[]'

Definition:

   This restraint, which will normally be used to restrain
   the total occupancy of an atom site, can be used to
   restrain the value of
   SUM(over the specified atoms){PARAMETER*COEFFICIENT}
   where PARAMETER will usually be the value of the occupancy
   (but other allowed quantities such as x, y and z can be
   specified in the enumeration) and COEFFICIENT is a user-defined
   number with a default value of 1.0.
   The restraint requires two loops, the first defines the
   atoms in each sum (class) and the second describes the
   properties of the class.

Example:

Example 1. This example gives the properties of the five classes given as examples in restr_parameter. The _*_class_id is the _list_reference and is the same as _*_class_id in the restr_parameter loop. The _*_parameter_type indicates the atomic parameter that is restrained. _*_target is the target value for the sum of the product of _restr_parameter_atom_coefficient and the value of the _*_parameter_type for the atom. _*_target_weight_sum gives the expectation value of the difference between the target and the refined value of sum(coefficient*parameter). _*_details gives a description of the restraint applied.

 
    loop_
    _restr_parameter_class_class_id
    _restr_parameter_class_parameter_type
    _restr_parameter_class_target
    _restr_parameter_class_target_weight_param
    _restr_parameter_class_details
       1 occupancy   0.8  0.01   'total occupation is 0.8'
       2 occupancy   1.0  0.001  'total occupation is 1.0'
       3 occupancy   2.0  0.01   'total charge is 2.0'
       4 position_y  0.5  0.002  'keep close to pseudo-mirror plane'
       5 position_x  0    0.01   'correlate position of O3 and O4'

Type: null

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Crystallographic Information Framework

Restraints dictionary version 1.0

Category RESTR_PARAMETER_CLASS

International Tables for Crystallography

Volume G: Definition and exchange of crystallographic data

Edited by S. R. Hall and B. McMahon

IUCrData