Description of induced nuclear fission with Skyrme energy functionals: Static potential energy surfaces and fission fragment properties

TLDR

Eighty years after its experimental discovery, a microscopic description of induced nuclear fission based solely on neutron–proton interactions and quantum many‑body methods remains a formidable challenge. The paper aims to develop a predictive microscopic framework for accurately calculating static properties of fission fragments in hot, thermal, or slow neutron‑induced fission, and introduces a general template for detailed fragment property description. The study uses nuclear density functional theory with Skyrme energy densities to compute Hartree‑Fock‑Bogoliubov potential energy surfaces for the 239Pu(n,f) reaction with up to five collective variables, and analyzes the scission point with advanced topological and quantum many‑body techniques. The results show that triaxial deformation significantly influences the fission barrier and scission, the Skyrme parameterization strongly affects deformation from ground state to scission, and accurate predictions of fragment properties at low neutron energies are achievable with current density functional theory.

Abstract

Eighty years after its experimental discovery, a microscopic description of induced nuclear fission based solely on the interactions between neutrons and protons and quantum many-body methods still poses formidable challenges. The goal of this paper is to contribute to the development of a predictive microscopic framework for the accurate calculation of static properties of fission fragments for hot fission and thermal or slow neutrons. To this end, we focus on the 239Pu(n,f) reaction and employ nuclear density functional theory with Skyrme energy densities. Potential energy surfaces are computed at the Hartree-Fock-Bogoliubov approximation with up to five collective variables. We find that the triaxial degree of freedom plays an important role, both near the fission barrier and at scission. The impact of the parameterization of the Skyrme energy density on deformation properties from the ground-state up to scission is also quantified. We introduce a general template for the detailed description of fission fragment properties. It is based on the careful analysis of the scission point, using both advanced topological methods and recently proposed quantum many-body techniques. We conclude that an accurate prediction of fission fragment properties at low incident neutron energies, although technologically demanding, should be within the reach of current nuclear density functional theory.