Developments in the calculation of fission potential-energy surfaces

We present calculations based on a realistic theoretical model of the multi-dimensional potential-energy surface of a fissioning nucleus. This surface guides the nuclear shape evolution from the ground state, over inner and outer saddle points, to the final configurations of separated fission fragments. Until recently, no calculation has properly explored a shape parameterization of sufficient dimensionality to permit the corresponding potential-energy surface to exhibit the multiple minima, valleys, saddle points and ridges that correspond to characteristic observables of the fission process. Here we calculate and analyze five-dimensional potential-energy landscapes based on grids of several million deformation points. We find that observed fission features such as different energy thresholds for symmetric and asymmetric fission and fission-fragment mass and kinetic-energy distributions are very closely related to properties of the valleys and mountain passes present in the calculated five-dimensional energy landscapes. We have also determined fission-barrier heights for 31 nuclei throughout the periodic system. (author)