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 86.0 % 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. Note - The particular type of ADP stored in this item is qualified by item _refine.pdbx_adp_type.

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