Fission barriers at the end of the chart of the nuclides

Abstract

We present calculated fission-barrier heights for 5239 nuclides for all nuclei between the proton and neutron drip lines with $171\ensuremath{\le}A\ensuremath{\le}330$. The barriers are calculated in the macroscopic-microscopic finite-range liquid-drop model with a 2002 set of macroscopic-model parameters. The saddle-point energies are determined from potential-energy surfaces based on more than 5 000 000 different shapes, defined by five deformation parameters in the three-quadratic-surface shape parametrization: elongation, neck diameter, left-fragment spheroidal deformation, right-fragment spheroidal deformation, and nascent-fragment mass asymmetry. The energy of the ground state is determined by calculating the lowest-energy configuration in both the Nilsson perturbed-spheroid $(\ensuremath{\epsilon})$ and the spherical-harmonic $(\ensuremath{\beta})$ parametrizations, including axially asymmetric deformations. The lower of the two results (correcting for zero-point motion) is defined as the ground-state energy. The effect of axial asymmetry on the inner barrier peak is calculated in the $(\ensuremath{\epsilon},\ensuremath{\gamma})$ parametrization. We have earlier benchmarked our calculated barrier heights to experimentally extracted barrier parameters and found average agreement to about 1 MeV for known data across the nuclear chart. Here we do additional benchmarks and investigate the qualitative and, when possible, quantitative agreement and/or consistency with data on $\ensuremath{\beta}$-delayed fission, isotope generation along prompt-neutron-capture chains in nuclear-weapons tests, and superheavy-element stability. These studies all indicate that the model is realistic at considerable distances in $Z$ and $N$ from the region of nuclei where its parameters were determined.