Multi-dimensional potential energy surfaces and non-axial octupole correlations in actinide and transfermium nuclei from relativistic mean field models

TL;DR

This paper introduces multi-dimensional covariant density functional theories to analyze complex nuclear shapes and octupole correlations in actinide and transfermium nuclei, revealing the importance of triaxiality and non-axial deformations.

Contribution

It develops a comprehensive theoretical framework for multi-dimensional nuclear shape analysis, including non-axial octupole correlations, and applies it to actinide nuclei to explore their potential energy surfaces.

Findings

Triaxiality significantly affects second fission barriers.

Non-axial octupole 2 correlations lower energy states in certain isotones.

Potential energy surfaces are sensitive to shape degrees of freedom.

Abstract

We have developed multi-dimensional constrained covariant density functional theories (MDC-CDFT) for finite nuclei in which the shape degrees of freedom \beta_{\lambda\mu} with even \mu, e.g., \beta_{20}, \beta_{22}, \beta_{30}, \beta_{32}, \beta_{40}, etc., can be described simultaneously. The functional can be one of the following four forms: the meson exchange or point-coupling nucleon interactions combined with the non-linear or density-dependent couplings. For the pp channel, either the BCS approach or the Bogoliubov transformation is implemented. The MDC-CDFTs with the BCS approach for the pairing (in the following labelled as MDC-RMF models with RMF standing for "relativistic mean field") have been applied to investigate multi-dimensional potential energy surfaces and the non-axial octupole $Y_{32}$-correlations in N=150 isotones. In this contribution we present briefly the formalism of MDC-RMF models and some results from these models. The potential energy surfaces with and without triaxial deformations are compared and it is found that the triaxiality plays an important role upon the second fission barriers of actinide nuclei. In the study of Y_{32}-correlations in N=150 isotones, it is found that, for 248Cf and 250Fm, \beta_{32} > 0.03 and the energy is lowered by the \beta_{32} distortion by more than 300 keV; while for 246Cm and 252No, the pocket with respect to \beta_{32} is quite shallow.