Equivalent isotropic atomic displacement parameter, Uequiv,
in angstroms squared, calculated as the geometric mean of
the anisotropic atomic displacement parameters.
Uequiv = (Ui Uj Uk)1/3
Un = the principal components of the orthogonalised Uij
Data Type
Data type code
float
Data type detail
int item types are the subset of numbers that are the floating
numbers.