  We present a new framework to treat the dissipation and fluctuation dynamics
associated with nucleon-nucleon scattering in heavy-ion collisions. The
two-body collision processes are effectively described in terms of the
diffusion of nucleons in viscous nuclear media, governed by a set of Langevin
equations in momentum space. The new framework combined with the usual mean
field dynamics can be used to simulate heavy-ion collisions at intermediate
energies. As a proof of principle, we simulate Au + Au reactions and obtain
results consistent with other existing codes under the same constrained
conditions. We also study the formation of fragments in Sn + Sn reactions at 50
MeV/nucleon, and results are discussed and compared with two other models
commonly employed for collisions.
