Exploring highly-deformed ground states involving the second intruder orbit in Z>50 even-even nuclei

TL;DR

This study systematically identifies highly deformed prolate ground states involving the second intruder orbit in Z>50 even-even nuclei using energy density functional theory, revealing characteristic deformation features and robustness across interactions.

Contribution

It provides the first systematic survey of such deformed states in heavy nuclei, highlighting the role of the second intruder orbit and deformation coupling effects.

Findings

Pronounced prolate minima at $eta_2 ext{≈}0.3$--0.4

Local enhancement of $eta_4$ at minima

Qualitative robustness across different Skyrme interactions

Abstract

We present a systematic survey of even-even nuclei with $Z>50$ to identify where a very large prolate configuration driven by the second intruder orbit emerges. Within the energy density functional theory framework, we find in representative cases a pronounced prolate minimum at quadrupole deformation $\beta_2\approx$ 0.3--0.4. A characteristic feature of these minima is a local enhancement of the hexadecapole ($\beta_4$) component relative to nearby deformations, which is a clear fingerprint of the $\beta_2$--$\beta_4$ coupling expected for the second intruder orbit. Representative comparisons among three Skyrme interactions show a similar appearance of the highly deformed minimum and a local enhancement of $\beta_4$ at the prolate minimum, indicating qualitative robustness with respect to the interaction. The resulting maps highlight specific heavy nuclei where highly deformed ground states are anticipated.