Shell stabilization of super- and hyperheavy nuclei without magic gaps

Quantum stabilization of superheavy elements is quantified in terms of the shell-correction energy. We compute the shell correction at spherical shape using self-consistent nuclear models: the non-relativistic Skyrme-Hartree- Fock approach and the relativistic mean-field model, for a number of parame trizations. All the forces applied predict a broad valley of shell stabiliz ation around Z = 120 and N = 172-184. We also predict two broad regions of shell stabilization in hyperheavy elements with N approximate to 258 and N approximate to 308. Due to the large single-particle level density, shell c orrections in the superheavy elements differ markedly from those in lighter nuclei. With increasing proton and neutron numbers, the regions of nuclei stabilized by shell effects become poorly localized in particle number, and the familiar pattern of shells separated by magic gaps is basically gone. (C) 2001 Published by Elsevier Science B.V.