Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. V. Extension to fission barriers

Abstract

Large-scale fission barrier calculations have been performed in the framework of the Skyrme-Hartree-Fock model. Our Hartree-Fock-Bogoliubov calculations restore broken symmetries such as translational invariance, particle-number conservation, parity, and, in a more approximate way, rotational invariance. Axial symmetry is imposed, but reflection asymmetry is allowed. The energy surface properties are analyzed with the flooding method. A large set of Skyrme interactions, which were fitted to all known masses under different specific constraints, is used to study the main effects influencing the energy surface and the barrier heights. The principal interaction used in the comparison with experimental barriers is BSk8, the force on which the HFB-8 mass table is based. We found that for nuclei with $92\ensuremath{\le}Z\ensuremath{\le}98$ the agreement of our calculations with experimental data is excellent; the rms deviation on the primary barriers is 0.722 MeV. For lighter nuclei, however, the calculated primary barriers are always too high because of the existence of a third barrier at very high deformations. However, our calculated superheavy barriers appear to be too low, although they are consistent with previous calculations.