Protein Data Bank exchange dictionary (pdbx) version 1.0521
_pdbx_reflns_twin.mean_F_square_over_mean_F2
Name:'_pdbx_reflns_twin.mean_F_square_over_mean_F2'
Definition:
The ideal statistics for twinned crystals. The values calculated with the acentric data are given below. Statistic Untwinned data Perfect twinned data <I^2>/<I>^2 2.0 1.5 <F>^2/<F^2> 0.785 0.865 References: Yeates, T.O. (1997) Methods in Enzymology 276, 344-358. Detecting and Overcoming Crystal Twinning. and information from the following on-line sites: CNS site http://cns.csb.yale.edu/v1.1/ CCP4 site http://www.ccp4.ac.uk/dist/html/detwin.html SHELX site http://shelx.uni-ac.gwdg.de/~rherbst/twin.html
Type: float
Mandatory item: yes
Category: pdbx_reflns_twin