Index

Core dictionary version 3.0.14

_refine_ls.extinction_method

Definition:

   
     Description of the extinction correction method applied with the
     data item _refine_ls.extinction_coef. This description should
     include information about the correction method, either 'Becker-
     Coppens' or 'Zachariasen'. The latter is sometimes referred to as
     the 'Larson' method even though it employs Zachariasen's formula.

     The Becker-Coppens procedure is referred to as 'type 1' when
     correcting secondary extinction dominated by the mosaic spread;
     as 'type 2' when secondary extinction is dominated by particle
     size and includes a primary extinction component; and as 'mixed'
     when there are types 1 and 2.
 
     For the Becker-Coppens method it is also necessary to set the
     mosaic distribution as either 'Gaussian' or 'Lorentzian'; and the
     nature of the extinction as 'isotropic' or 'anisotropic'. Note
     that if either the 'mixed' or 'anisotropic' corrections are applied
     the multiple coefficients cannot be contained in the
     _refine_ls.extinction_coef and must be listed in _refine.special_details.

     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.

Type: Text

Category:
refine_ls