Item _refine.overall_FOM_free_R_set

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 function
                               of the first kind
               X             = sigma_A |E_o| |E_c|/SIGMA
               E_o, E_c      = normalized observed and calculated structure
                               factors
               sigma_A       =  SQRT(Sigma_P/Sigma_N)
                               estimated using maximum likelihood
               Sigma_P       = sum_{atoms in model} f^2
               Sigma_N       = sum_{atoms in crystal} f^2
               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 diffracting plane

               Ref: (sigma_A estimation) "Refinement of Macromolecular
                    Structures by the Maximum-Likelihood Method",
                    Murshudov, G. N., Vagin A. A. & Dodson, E. J. (1997).
                    Acta Cryst. D53, 240-255.

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Mandatory Code

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