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Core CIF Dictionary version 2.3

_refine_ls_extinction_coef

Name

'_refine_ls_extinction_coef'

Category: refine

Data type: numb (with optional s.u. in parentheses)

Example: 3472(52) 'Zachariasen coefficient r* = 0.347(5) E04'

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,
         129-153.
         Zachariasen, W. H. (1967). Acta Cryst. 23, 558-564.
         Larson, A. C. (1967). Acta Cryst. 23, 664-665.
 


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