Potential Energy Surfaces of Actinide Nuclei from a Multi-dimensional Constraint Covariant Density Functional Theory: Barrier Heights and Saddle Point Shapes

TL;DR

This paper introduces a multi-dimensional constrained covariant density functional theory to calculate actinide nuclei potential energy surfaces, revealing the significant impact of triaxial and octupole deformations on fission barrier heights and shapes.

Contribution

It develops a novel multi-dimensional constrained covariant density functional theory to explore deformation effects on actinide nuclei's potential energy surfaces.

Findings

Triaxiality lowers the inner and outer fission barriers.

Inclusion of triaxial deformation improves agreement with experimental barrier data.

Outer barrier lowering is 0.5 to 1 MeV, or 10-20% of barrier height.

Abstract

For the first time the potential energy surfaces of actinide nuclei in the $(\beta_{20}, \beta_{22}, \beta_{30})$ deformation space are obtained from a multi-dimensional constrained covariant density functional theory. With this newly developed theory we are able to explore the importance of the triaxial and octupole shapes simultaneously along the whole fission path. It is found that besides the octupole deformation, the triaxiality also plays an important role upon the second fission barriers. The outer barrier as well as the inner barrier are lowered by the triaxial deformation compared with axially symmetric results. This lowering effect for the reflection asymmetric outer barrier is 0.5 $\sim$ 1 MeV, accounting for $10 \sim 20%$ of the barrier height. With the inclusion of the triaxial deformation, a good agreement with the data for the outer barriers of actinide nuclei is achieved.