Core dictionary (coreCIF) version 2.3.1

_atom_site_B_iso_or_equiv

Definition:

   Isotropic atomic displacement parameter, or equivalent isotropic
   atomic displacement parameter, B(equiv), in angstroms squared,
   calculated from anisotropic displacement components.

   B(equiv) = (1/3) sum~i~[sum~j~(B^ij^ a*~i~ a*~j~ a~i~ a~j~)]

   a     = the real-space cell lengths
   a*    = the reciprocal-space cell lengths
   B^ij^ = 8 pi^2^ U^ij^

   Ref: Fischer, R. X. & Tillmanns, E. (1988). Acta Cryst. C44,
        775-776.

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

Appears in list containing _atom_site_label

Related items : _atom_site_B_equiv_geom_mean

Type: numb

Category: atom_site