Data Item _refine.overall_FOM_free_R_set
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General 
- Item name
- _refine.overall_FOM_free_R_set
- Category name
- refine
- Attribute name
- overall_FOM_free_R_set
- Required in PDB entries
- no
- Used in current PDB entries
- Yes, in about 0.000 % of entries
Item Description
Average figure of merit of phases of reflections not included
in the refinement.
This value is derived from the likelihood function.
FOM = I_1(X)/I_0(X)
I_0, I_1 = zero- and first-order modified Bessel functions
of the first kind
X = sigma_A |E_o| |E_c|/SIGMA
E_o, E_c = normalized observed and calculated structure
factors
sigma_A = <cos 2 pi s delta_x> SQRT(Sigma_P/Sigma_N)
estimated using maximum likelihood
Sigma_P = sum_{atoms in model} f2
Sigma_N = sum_{atoms in crystal} f2
f = form factor of atoms
delta_x = expected error
SIGMA = (sigma_{E;exp})2 + epsilon [1-(sigma_A)2]
sigma_{E;exp} = uncertainties of normalized observed
structure factors
epsilon = multiplicity of the diffracting plane
Ref: Murshudov, G. N., Vagin, A. A. & Dodson, E. J. (1997).
Acta Cryst. D53, 240-255.
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]+)?
Aliases
| Alias Item Name | Dictionary Name | Dictionary Version |
|---|---|---|
| _refine.ebi_overall_FOM_free_Rset | ebi_extensions | 1.0 |