Hyperheavy spherical and toroidal nuclei: The role of shell structure

Model for independent particle motion

“…It is based on the results of the calculations presented in Refs. [61,62,63]. The bands (shown by gray color) of spherical nuclei along proton and neutron numbers 8, 20, 28, 50 and 82 (as well as for neutron number N = 126) are seen in this figure.…”

“…Thus, the richness of nuclear structure seen in experimentally known part of nuclear landscape is replaced by a more uniform structure of the nuclear landscape in the region of hyperheavy (Z ≥ 126) nuclei dominated by toroidal nuclei [61,63]. This transition from compact ellipsoidal-like shapes to non-compact toroidal shapes is driven by the enhancement of the role of Coulomb interaction with increasing Z [63].…”

“…7) is penetrated only by three islands (shown in gray color) of potentially stable spherical hyperheavy nuclei. Their existence is due to substantial proton Z = 154 and 186 and neutron N = 228, 308, and 406 spherical shell gaps [61] and substantial fission barriers around spherical minima [61,63]. However, these states are highly excited with respect of minima corresponding to toroidal shapes.…”

“…However, these states are highly excited with respect of minima corresponding to toroidal shapes. They could become the ground states if relevant toroidal minima are unstable with respect of so-called sausage deformations [61,68].…”

“…For example, the position of two-neutron drip line of ellipsoidal nuclei depends sensitively on the single-particle energies of highj states located in the vicinity of neutron continuum threshold [69]. The transition from ellipsoidal to toroidal shapes drastically modifies the underlying single-particle structure and as a result lowers the energy of the Fermi level for protons [61]. As a consequence, a substantial shift of the two-proton drip line from its expected position for ellipsoildal shapes (shown by dashed orange line in Fig.…”