Fourier Shell Correlation (FSC) between model and
observed structure factors for reflections included in refinement.
FSC is a measure of the agreement between observed
and calculated structure factors as complex numbers.
(sum(|Fo| |Fc| fom cos(phic-phio)))
FSCwork = --------------------------------------
(sum(|Fo|2) (sum(|Fc|2)))1/2
|Fo| = amplitude of observed structure factor
|Fc| = amplitude of calculated structure factor
phio = phase of observed structure factor
phic = phase of calculated structure factor
fom = figure of merit of the experimental phases.
Summation is carried over all working reflections in the resolution shell.
Ref: Rosenthal P.B., Henderson R.
"Optimal determination of particle orientation, absolute hand,
and contrast loss in single-particle electron cryomicroscopy.
Journal of Molecular Biology. 2003;333(4):721-745, equation (A6).