T-2, Nuclear and Particle Physics, Astrophysics and Cosmology

Fission of 240Pu in time-dependent density functional theory

Ionel Stetcu

The density functional theory (DFT) provides the only microscopic framework suitable for description of heavy nuclei and feasible on today’s computers. Instead of computing the full many-body wave function, one can determine only the one-body density within the Density Functional Theory (DFT), the highly successful approach pioneered by Kohn (Nobel prize, 1998), Hohenberg, and Sham (1964-1965) for many-electron systems in chemistry and condensed matter physics. Within the extension to time-dependent DFT (TDDFT), fission dynamics becomes computationally manageable and, hence, a microscopic description feasible. To study quantum dynamics we developed a real-time DFT extension, explicitly including the dynamics of the crucial pairing correlations, used existing reasonably accurate energy density functionals (EDF), and implemented it on leadership class computers. In this talk, I will present the main characteristics of the fission fragments in TDDFT, from average mass and charge, to average total kinetic energy (TKE) and sharing of the excitation energy. Even if no complete process description can be achieved yet (e.g. no neutron and gamma-ray emissions from fission fragments, which require very long evolution times), the information provided by the dynamics can be used as input into phenomenological Hauser-Feshbach codes that treat the de-excitation of fission fragments. TKE and mass/charge yields are directly compared with experimental data with reasonably good agreement and with no fitting parameters.


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