Octupole deformation in the ground states of even-even nuclei: a global analysis within the covariant density functional theory

TL;DR

This study systematically analyzes octupole deformation in even-even nuclei using covariant density functional theory, predicting a new deformation region around Z~98, N~196, and comparing relativistic and non-relativistic models.

Contribution

It introduces a comprehensive covariant density functional analysis of octupole deformation across a wide range of nuclei, predicting a new deformation region and assessing model uncertainties.

Findings

Predicted a new octupole deformation region around Z~98, N~196.

Compared relativistic and non-relativistic model predictions.

Found increased size of octupole deformed nuclei region compared to experimental data.

Abstract

A systematic investigation of octupole deformed nuclei is presented for even-even systems with $Z\leq 106$ located between the two-proton and two-neutron drip lines. For this study we use five most up-to-date covariant energy density functionals of different types, with a non-linear meson coupling, with density dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov (RHB) theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole deformed nuclei. In addition, a detailed comparison with the predictions of non-relativistic models is performed. A new region of octupole deformation, centered around $Z\sim 98, N\sim 196$ is predicted for the first time. In terms of its size in the $(Z,N)$ plane and the impact of octupole deformation on binding energies this region is similar to the best known region of octupole deformed nuclei centered at $Z\sim 90, N\sim 136$. For the later island of octupole deformed nuclei, the calculations suggest substantial increase of its size as compared with available experimental data.