Analytical models representing X-ray form factors of ions.

Parameters in analytical models for X-ray form factors of ions f 0 (s), based on the inverse Mott-Bethe formula involving a variable number of Gaussians, are determined for a wide range of published data sets {s, f 0 (s)}. The models reproduce the calculated form-factor values close to what is expected from a uniform statistical distribution with limits determined by their precision. For different ions associated with the same atom, the number of Gaussians in the models decreases with increasing net positive charge.