Spectroscopy of reflection-asymmetric nuclei with relativistic energy density functionals

TL;DR

This paper systematically analyzes reflection-asymmetric nuclei using a relativistic energy density functional-based collective Hamiltonian, accurately describing low-energy spectra and revealing octupole collectivity across multiple isotopic chains.

Contribution

It introduces a microscopic QOCH model with relativistic mean-field parameters that effectively reproduces empirical data and predicts octupole phenomena in various nuclei.

Findings

Accurate description of low-energy quadrupole and octupole states.

Evidence of octupole collectivity in multiple isotopic chains.

Consistent predictions with both relativistic and non-relativistic models.

Abstract

Quadrupole and octupole deformation energy surfaces, low-energy excitation spectra and transition rates in fourteen isotopic chains: Xe, Ba, Ce, Nd, Sm, Gd, Rn, Ra, Th, U, Pu, Cm, Cf, and Fm, are systematically analyzed using a theoretical framework based on a quadrupole-octupole collective Hamiltonian (QOCH), with parameters determined by constrained reflection-asymmetric and axially-symmetric relativistic mean-field calculations. The microscopic QOCH model based on the PC-PK1 energy density functional and $\delta$-interaction pairing is shown to accurately describe the empirical trend of low-energy quadrupole and octupole collective states, and predicted spectroscopic properties are consistent with recent microscopic calculations based on both relativistic and non-relativistic energy density functionals. Low-energy negative-parity bands, average octupole deformations, and transition rates show evidence for octupole collectivity in both mass regions, for which a microscopic mechanism is discussed in terms of evolution of single-nucleon orbitals with deformation.