Mass Formula Consistent with Nuclear-Matter Calculations vs Conventional Mass-Law Extrapolations

The energy-density functional proposed by Brueckner etal. is used to calculate the average nuclear-binding-energy surface on the $N-Z$ plane at $\beta$ stability ± about 40 units. The equibinding contours are compared with those predicted by recent liquid-droplet models. Normally, some disagreement begins about 15 units away from the region of known nuclei. The deviations towards lower binding are significant for neutron-rich transuranium (superheavy) nuclei. This would seem to indicate a physically important uncertainty in conventional masslaw extrapolations. The semiempirical dependence on neutron excess cannot be established very well, because of the narrowness of the region of known isotopes. The energy-density functional, on the other hand, incorporates the present knowledge about nuclear matter - including recent neutron-matter results. Our disagreement with other extrapolations, therefore, questions the validity of stability and formation (e.g., $r$-process) calculations based on conventional mass formulas.