Multidimensionally-constrained relativistic Hartree-Bogoliubov study of nuclear spontaneous fission

TL;DR

This study uses the multidimensionally-constrained relativistic Hartree-Bogoliubov model to analyze nuclear spontaneous fission paths, energies, and half-lives, highlighting the impact of collective degrees of freedom and inertia calculations.

Contribution

It introduces a comprehensive MDC-RHB approach to study fission, comparing different energy density functionals and inertia calculations for the first time.

Findings

Fission paths depend on collective inertia approximations.

Predicted half-lives vary with the choice of functional and inertia model.

Deformation energy surfaces and collective potentials are characterized for Fm isotopes.

Abstract

Recent microscopic studies, based on the theoretical framework of nuclear energy density functionals, have analyzed dynamic (least action) and static (minimum energy) fission paths, and it has been shown that in addition to the important role played by nonaxial and/or octupole collective degrees of freedom, fission paths crucially depend on the approximations adopted in calculating the collective inertia. The dynamics of spontaneous fission of $^{264}$Fm and $^{250}$Fm is explored. The fission paths, action integrals and the corresponding half-lives predicted by the functionals PC-PK1 and DD-PC1 are compared and, in the case of $^{264}$Fm, discussed in relation with recent results obtained using the HFB model based on the Skyrme functional SkM$^*$ and a density dependent mixed pairing interaction. Deformation energy surfaces, collective potentials, and perturbative and nonperturbative cranking collective inertia tensors are calculated using the multidimensionally-constrained relativistic Hartree-Bogoliubov (MDC-RHB) model, with the energy density functionals PC-PK1 and DD-PC1. Pairing correlations are treated in the Bogoliubov approximation using a separable pairing force of finite range. The least-action principle is employed to determine dynamic spontaneous fission paths.