  The moment of inertia for nuclear collective rotations was derived within the
semiclassical approach based on the cranking model and the Strutinsky
shell-correction method by using the non-perturbative periodic-orbit theory in
the phase space variables. This moment of inertia for adiabatic
(statistical-equilibrium) rotations can be approximated by the generalized
rigid-body moment of inertia accounting for the shell corrections of the
particle density. A semiclassical phase-space trace formula allows to express
quite accurately the shell components of the moment of inertia in terms of the
free-energy shell corrections for integrable and partially chaotic Fermi
systems, in good agreement with the quantum calculations.
