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Core CIF Dictionary version 2.3




Category: atom_site

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

Must appear in a looped list containing '_atom_site_label'

Enumeration range: 0.0 -> infinity

Related item(s), related function(s):
'_atom_site_B_iso_or_equiv' alternate '_atom_site_U_equiv_geom_mean' conversion

Units: A^2^ ( angstroms squared)


   Equivalent isotropic atomic displacement parameter, B(equiv),
   in angstroms squared, calculated as the geometric mean of
   the anisotropic atomic displacement parameters.

   B(equiv) = (B~i~ B~j~ B~k~)^1/3^

   B~n~  = the principal components of the orthogonalised B^ij^

   The IUCr Commission on Nomenclature recommends against the use
   of B for reporting atomic displacement parameters. U, being
   directly proportional to B, is preferred.

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