Microscopic analysis of the octupole phase transition in Th isotopes

TL;DR

This paper investigates the phase transition between stable octupole deformation and vibrations in thorium isotopes using a microscopic nuclear density functional theory approach, revealing a shape phase transition in these nuclei.

Contribution

It introduces a microscopic framework combining density functional theory and boson models to analyze octupole shape transitions in Th isotopes.

Findings

Identification of a phase transition between octupole-deformed and octupole-soft shapes.

Systematic energy surface analysis supports the occurrence of shape phase transition.

Computed excitation spectra align with the predicted shape transition.

Abstract

A shape phase transition between stable octupole deformation and octupole vibrations in Th nuclei is analyzed in a microscopic framework based on nuclear density functional theory. The relativistic functional DD-PC1 is used to calculate axially-symmetric quadrupole-octupole constrained energy surfaces. Observables related to order parameters are computed using an interacting-boson Hamiltonian, with parameters determined by mapping the microscopic energy surfaces to the expectation value of the Hamiltonian in the boson condensate. The systematics of constrained energy surfaces and low-energy excitation spectra point to the occurrence of a phase transition between octupole-deformed shapes and shapes characterized by octupole-soft potentials.