Nonequilibrium Green's function approach to low-energy fission dynamics: Fluctuations in fission reactions

We present a microscopic modeling for a decay of a heavy compound nucleus, starting from a nucleonic degree of freedom. To this end, we develop an approach based on a nonequilibrium Green's function, which is combined with a configuration-interaction approach based on a constrained density-functional theory. We apply this approach to a barrier-top fission of 236U, restricting the model space to seniority zero configurations of neutrons and protons. We particularly focus on the distribution of the fission probability. We find that it approximately follows the chi 2 distribution with the number of degrees of freedom v of the order of 1, which is consistent with the experimental finding. We also show that v corresponds to the number of those eigenstates of the many-body Hamiltonian which have significant components on both sides of a fission barrier and at the same time whose eigenenergy is close to the excitation energy of the system.