Data Item _pdbx_reflns_twin.mean_F_square_over_mean_F2

General

Item name
_pdbx_reflns_twin.mean_F_square_over_mean_F2
Category name
pdbx_reflns_twin
Attribute name
mean_F_square_over_mean_F2
Required in PDB entries
no
Used in currrent PDB entries
No

Item Description

The ideal statistics for twinned crystals. The values calculated with the acentric data are given below. Statistic Untwinned data Perfect twinned data <I2>/<I>2 2.0 1.5 <F>2/<F2> 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

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]+)?