Mass parameters for large amplitude collective motion: A perturbative microscopic approach

The adiabatic limit of the time-dependent Hartree–Fock–Bogoliubov approximation is studied in the canonical basis for a rather wide class of collective modes. As a first step towards a fully selfconsistent solution, we study mass parameters where the effects due to the time-odd part of the mean fields are neglected, but where the static rearrangement of the generalized cranking operator is taken into account. Corresponding inertia parameters are compared with those resulting from currently used ansatz in microscopic accounts of the low energy nuclear collective dynamics. For the particular case of the axial quadrupole motion and using the Gogny D1S effective interaction, we show that our mass parameters exhibit strong variations as functions of the deformation whose origins are traced back to the rearrangement of both the Hartree–Fock and pairing fields. The physical consequences of these variations depend of the time scales of the studied collective motions and are illustrated in the context of superdeformed states in the A∼150 region and of the lifetime of a fission isomer in the actinide region.