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Transfer from msCIF: refine_ls_class category



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:

#####################
## REFINE_LS_CLASS ##   
#####################

data_refine_ls_class_[]
    _name                        '_refine_ls_class_[]'
    _category                    category_overview
    _type                        null
    loop_ _example
          _example_detail
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
;
    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.]
;
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      _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.
;

data_refine_ls_class_d_res_high
    _name                        '_refine_ls_class_d_res_high'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference              '_refine_ls_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the highest resolution in angstroms
               for the spacing in the reflections used in refinement. This is
               the lowest d value in a reflection class.
;

data_refine_ls_class_d_res_low
    _name                        '_refine_ls_class_d_res_low'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference              '_refine_ls_class_code'
    _enumeration_range           0.0:
    _units                       A
    _units_detail                'Angstroms'
    _definition
;              For each reflection class, the lowest resolution in angstroms 
               for the spacing in the reflections used in refinement. This is
               the highest d value in a reflection class.
;

data_refine_ls_class_R_factor_
    loop_ _name                  '_refine_ls_class_R_factor_all'
                                 '_refine_ls_class_R_factor_gt'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference              '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factors for all 
               reflections, and for significantly intense reflections (see 
               _reflns_threshold_expression) and included in the refinement.
               The reflections also satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
               This is the conventional R factor. 
                        R=sum|F(obs)-F(calc)|/sum|F(obs)|
               F(obs)=the observed structure-factor amplitudes, F(calc)=the 
               calculated structure-factor amplitudes, and the sum is taken over
               the specified reflections. See also 
               _refine_ls_class_wR_factor_all definitions.
;

data_refine_ls_class_R_Fsqd_factor
    _name                        '_refine_ls_class_R_Fsqd_factor'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference              '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(F^2^) calculated
               on the squares of the observed and calculated structure factors,
               for the reflections judged significantly intense (i.e. satisfying
               the threshold specified by _reflns_threshold_expression) and 
               included in the refinement. The reflections also satisfy the 
               resolution limits established by _refine_ls_class_d_res_high and
               _refine_ls_class_d_res_low.
                        R(F^2^)=sum|F(obs)^2^-F(calc)^2^|/sum|F(obs)^2^|
               F(obs)^2^=squares of the observed structure-factor amplitudes, 
               F(calc)^2^=squares of the calculated structure-factor amplitudes,
               and the sum is taken over the specified reflections.
;

data_refine_ls_class_R_I_factor
    _name                        '_refine_ls_class_R_I_factor'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference              '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the residual factor R(I) for  
               estimated reflection intensities, for the reflections judged
               significantly intense (i.e. satisfying the threshold specified
               by _reflns_threshold_expression) and included in the refinement.
               This is most often calculated in Rietveld refinements
               of powder data, where it is referred to as R~B~ or R~Bragg~
                        R(I)=sum|I(obs)-I(calc)|/sum|I(obs)|
               I(obs)=the net observed intensities, I(calc)=the net calculated
               intensities, and the sum is taken over the specified reflections
;

data_refine_ls_class_wR_factor_all
    _name                        '_refine_ls_class_wR_factor_all'
    _category                    refine_ls_class
    _type                        numb
    _list                        yes
    _list_reference              '_refine_ls_class_code'
    _enumeration_range           0.0:
    _definition
;              For each reflection class, the weighted residual factors for all 
               reflections and included in the refinement. The reflections also
               satisfy the resolution limits established by
               _refine_ls_class_d_res_high and _refine_ls_class_d_res_low.
                        wR=sum|w|Y(obs)-Y(calc)|^2^|^1/2^/sum|wY(obs)^2^|
               Y(obs)=the observed amplitude specified by 
               _refine_ls_structure_factor_coef, Y(calc)=the calculated 
               amplitude specified by _refine_ls_structure_factor_coef, w=the
               least-squares weight, and the sum is taken over the specified 
               reflections. See also _refine_ls_class_R_factor_ definitions.
;

data_refine_ls_class_code
    _name                        '_refine_ls_class_code'
    _category                    refine_ls_class
    _type                        char
    _list                        yes
    _list_link_parent            '_diffrn_reflns_class_code'
    loop_ _example               '1'
                                 'm1'
                                 's2'
    _definition
;              The code identifying a certain reflection class. This code must 
               match a _diffrn_reflns_class_code.
;


_______________________________________________________________________________
Brian McMahon                                             tel: +44 1244 342878
Research and Development Officer                          fax: +44 1244 314888
International Union of Crystallography                  e-mail:  bm@iucr.ac.uk
5 Abbey Square, Chester CH1 2HU, England                         bm@iucr.org


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