Data Item _refine.overall_FOM_free_R_set


Item name
Category name
Attribute name
Required in PDB entries
Used in current PDB entries
Yes, in about 0.001 % 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
Data type detail
float item types are the subset of numbers that are the floating numbers.
Primitive data type code
Regular expression


Alias Item Name Dictionary Name Dictionary Version
_refine.ebi_overall_FOM_free_Rset ebi_extensions 1.0