Index

Core dictionary version 3.3.0

_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 atomic 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 vectors
    a*    = the reciprocals of the direct-space cell lengths
    B^ij^ = 8 π^2^ U^ij^

    Reference: 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.

Type: Real

Units: angstrom_squared

Category:
atom_site