  Collective mass tensor derived from the cranking approximation to the
adiabatic time-dependent Hartree-Fock-Bogoliubov (ATDHFB) approach is compared
with that obtained in the Gaussian Overlap Approximation (GOA) to the generator
coordinate method. Illustrative calculations are carried out for
one-dimensional quadrupole fission pathways in 256Fm. It is shown that the
collective mass exhibits strong variations with the quadrupole collective
coordinate. These variations are related to the changes in the intrinsic shell
structure. The differences between collective inertia obtained in cranking and
perturbative cranking approximations to ATDHFB, and within GOA, are discussed.
