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Macromolecular dictionary (mmCIF) version 2.0.09

_refine.ls_extinction_coef

Name:
'_refine.ls_extinction_coef'

Definition:

   The extinction coefficient used to calculate the correction
   factor applied to the structure-factor data. The nature of the
   extinction coefficient is given in the definitions of
   _refine.ls_extinction_expression and
   _refine.ls_extinction_method.

   For the 'Zachariasen' method it is the r* value; for the
   'Becker-Coppens type 1 isotropic' method it is the 'g' value,
   and for 'Becker-Coppens type 2 isotropic' corrections it is
   the 'rho' value. Note that the magnitude of these values is
   usually of the order of 10000.

   Ref:  Becker, P. J. & Coppens, P. (1974). Acta Cryst. A30,
         129-47, 148-153.
         Zachariasen, W. H. (1967). Acta Cryst. 23, 558-564.
         Larson, A. C. (1967). Acta Cryst. 23, 664-665.

Example:

3472 Zachariasen coefficient r* = 0.347 E04

Type: float

Type conditions: esd

Mandatory item: no

Alias:
_refine_ls_extinction_coef (cif_core.dic version 2.0.1)

Related item: _refine.ls_extinction_coef_esd (associated_esd)

Category: refine