Crystallographic Information Framework

[CIF logo]


Core dictionary (coreCIF) version 2.4.5




   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,

   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
The permitted range is 0.0 -> infinity

Related items : _atom_site_B_equiv_geom_mean (alternate)
_atom_site_U_iso_or_equiv (conversion)

Type: numb

Category: atom_site