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International
Tables for Crystallography Volume G Definition and exchange of crystallographic data Edited by J. R. Hester and B. McMahon © International Union of Crystallography 2026 |
International Tables for Crystallography (2026). Vol. G. Early view chapter
https://doi.org/10.1107/97809553602060001011 Chapter 4.2 Core dictionary (coreCIF) |
Core dictionary version 3.3.0
_refine_ls.abs_structure_Flack
Name:_refine_ls.abs_structure_Flack
Aliases:
_refine_ls_abs_structure_Flack
_refine.ls_abs_structure_Flack
Definition:
The measure of absolute structure as defined by Flack (1983).
For centrosymmetric structures, the only permitted value, if
the data item is present, is 'inapplicable', represented by '.' .
For noncentrosymmetric structures, the value must lie in the
99.97% Gaussian confidence interval -3u =< x =< 1 + 3u and a
standard uncertainty u must be supplied. The
_enumeration.range of 0.0:1.0 is correctly interpreted as
meaning (0.0 - 3u) =< x =< (1.0 + 3u).
Reference: Flack, H. D. (1983). Acta Cryst. A39, 876-881.
Type: Real
Units: none
The permitted range is 0.0 → 1.0
Category:
refine_ls
