Data Item _refine.pdbx_pd_Marquardt_correlation_coeff
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General 
- Item name
- _refine.pdbx_pd_Marquardt_correlation_coeff
- Category name
- refine
- Attribute name
- pdbx_pd_Marquardt_correlation_coeff
- Required in PDB entries
- no
- Used in currrent PDB entries
- No
Item Description
The correlation coefficient between the observed and
calculated structure factors for reflections included in
the refinement. This correlation factor is found in the
fitting using the Levenberg-Marquardt algorithm to search
for the minimum value of chisquare. Almost all computer
codes for Rietveld refinement employ the Gauss-Newton algorithm
to find parameters which minimize the weighted sum of squares
of the residuals.
A description of the equations is given on
http://www.water.hut.fi/tkarvone/fr_org_s.htm
Data Type 
- Data type code
- float
- Data type detail
- float item types are the subset of numbers that are the floating numbers.
- Primitive data type code
- numb
- Regular expression
- -?(([0-9]+)[.]?|([0-9]*[.][0-9]+))([(][0-9]+[)])?([eE][+-]?[0-9]+)?