**Definition:**

Equivalent isotropic atomic displacement parameter, B(equiv), in angstroms squared, calculated as the geometric mean of the anisotropic atomic displacement parameters. B(equiv) = (B~i~ B~j~ B~k~)^1/3^ B~n~ = the principal components of the orthogonalized B^ij^ 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_iso_or_equiv (alternate)

_atom_site_U_equiv_geom_mean (conversion)

**Type:** numb

**Category:** atom_site

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