  In this letter, we outline a methodology to calculate microscopically mass
and charge distributions of spontaneous fission yields. We combine the
multi-dimensional minimization of collective action for fission with stochastic
Langevin dynamics to track the relevant fission paths from the ground-state
configuration up to scission. The nuclear potential energy and collective
inertia governing the tunneling motion are obtained with nuclear density
functional theory in the collective space of shape deformations and pairing. We
obtain a quantitative agreement with experimental data and find that both the
charge and mass distributions in the spontaneous fission of 240Pu are sensitive
both to the dissipation in collective motion and to adiabatic characteristics.
