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Shape coexistence and triaxiality in the superheavy nuclei

Abstract

Superheavy nuclei represent the limit of nuclear mass and charge; they inhabit the remote corner of the nuclear landscape, whose extent is unknown. The discovery of new elements with atomic numbers Z ≥ 110 has brought much excitement to the atomic and nuclear physics communities. The existence of such heavy nuclei hangs on a subtle balance between the attractive nuclear force and the disruptive Coulomb repulsion between protons that favours fission. Here we model the interplay between these forces using self-consistent energy density functional theory; our approach accounts for spontaneous breaking of spherical symmetry through the nuclear Jahn–Teller effect. We predict that the long-lived superheavy elements can exist in a variety of shapes, including spherical, axial and triaxial configurations. In some cases, we anticipate the existence of metastable states and shape isomers that can affect decay properties and hence nuclear half-lives.

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Figure 1: Deformation properties of even–even superheavy nuclei calculated self-consistently in the (N,Z)-plane with the SLy4 nuclear energy density functional.
Figure 2: Qα values for even–even nuclei with 96 ≤ Z ≤ 118 obtained in the self-consistent calculations using the energy density functional SLy4.
Figure 3: Potential energy surfaces of the members of the α-decay chains of 294120 (ac) and 292116 (df) in the (Q20, Q22) plane calculated with the SLy4 energy density functional.
Figure 4: Contour map of the energy difference between oblate and prolate minima (or saddle points) in the energy surface of superheavy even–even nuclei.
Figure 5: Single-proton (a, b) and single-neutron (c, d) energy levels in the superheavy nucleus 292116176 obtained in self-consistent calculations with the SLy4 energy density functional.

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Acknowledgements

We thank M. Bender, J. Dobaczewski and M. Stoyer for discussions. This work was supported in part by the US Department of Energy, by the National Nuclear Security Administration under the Stewardship Science Academic Alliances programme, by the Belgian Science Policy Office, by NATO, and by the Polish Committee for Scientific Research (KBN).

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Correspondence to P.-H. Heenen.

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Ćwiok, S., Heenen, PH. & Nazarewicz, W. Shape coexistence and triaxiality in the superheavy nuclei. Nature 433, 705–709 (2005). https://doi.org/10.1038/nature03336

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