Core dictionary (coreCIF) version 2.4.5
'_refine_diff_density_max' '_refine_diff_density_min' '_refine_diff_density_rms'
The largest and smallest values and the root-mean-square deviation, in electrons per angstrom cubed, of the final difference electron density. The *_rms value is measured with respect to the arithmetic mean density and is derived from summations over each grid point in the asymmetric unit of the cell. This quantity is useful for assessing the significance of *_min and *_max values, and also for defining suitable contour levels.