The collision term has been deduced based on the effective Lagrangian
in addition to the mean-field. We propose the momentum- and density-de
pendent coupling strengths for scalar and vector fields. The saturatio
n properties of nuclear matter, the experimental data of the energy-de
pendent optical potential and the mean free path in the nuclei can be
reproduced simultaneously. The in-medium n - n cross section has also
been calculated for different densities and energies, our results are
consistent with Dirac-Brueckner-Hartree-Fock calculations.