  Careful theoretical studies of the nuclear collective inertia based on the
non-relativistic mean-field theory and the cranking model indicate that the
moments of inertia of the super-deformed nuclei calculated using various
standard methods and parameterizations exceed systematically the experimental
values. Similarly, but for other reasons the relativistic cranking calculations
based on the relativistic mean field method present, in our opinion, a
different class of systematic deviations from experiment. The origin and
possible explanations of these deviations are discussed briefly.
