Five-dimensional potential-energy surfaces and coexisting fission modes in heavy nuclei

We calculate complete fission potential-energy surfaces versus five shape coordinates: elongation, neck diameter, light-fragment deformation, heavy-fragment deformation, and mass asymmetry for even nuclei in the range 82≤Z≤100. The potential energy is calculated in terms of the macroscopic-microscopic model with a folded-Yukawa single-particle potential and a Yukawa-plus-exponential macroscopic model in the three-quadratic-surface parameterization. The structure of the calculated energy landscapes exhibits multiple valleys leading to different scission configurations. The properties of these valleys and the saddle-points at the beginning of these valleys can be directly related to bimodal fission properties observed in the radium region, in the light-actinide region, and in the fermium region). The rms deviation between calculated and experimental fission-barrier heights is only 1.08 MeV for 31 nuclei from 70Se to 252Cf