Data Item _atom_site.B_iso_or_equiv

General

Item name
_atom_site.B_iso_or_equiv
Category name
atom_site
Attribute name
B_iso_or_equiv
Required in PDB entries
no
Used in current PDB entries
Yes, in about 100.0 % of entries

Item Description

Isotropic atomic displacement parameter, or equivalent isotropic atomic displacement parameter, Beq, calculated from the anisotropic displacement parameters. Beq = (1/3) sumi[sumj(Bij Ai Aj a*i a*j)] A = the real space cell lengths a* = the reciprocal space cell lengths Bij = 8 pi2 Uij 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.

Data Type

Data type code
float
Data type detail
float item types are the subset of numbers that are the floating numbers.
Primitive data type code
numb
Regular expression
-?(([0-9]+)[.]?|([0-9]*[.][0-9]+))([(][0-9]+[)])?([eE][+-]?[0-9]+)?
Units
8pi2_angstroms_squared

Aliases

Alias Item Name Dictionary Name Dictionary Version
_atom_site_B_iso_or_equiv cif_core.dic 2.0.1