ANALYSIS OF ISOSPIN DEPENDENCE OF NUCLEAR COLLECTIVE FLOW IN AN ISOSPIN-DEPENDENT QUANTUM MOLECULAR-DYNAMICS MODEL

Within the framework of an isospin-dependent quantum molecular dynamic s model in which the initial neutron and proton densities are sampled according to the densities calculated from the Skyrme-Hartree-Fock met hod and the initial Fermi momenta of neutrons and protons are calculat ed from the Fermi gas model, we study systematically the transverse co llective flow of different fragment types at an energy of 55 MeV/nucle on and the balance energy in the reactions Fe-58+Fe-58 and Ni-58+Ni-58 . Th, results from the present calculations indicate that the neutron- rich system (Fe-58+Fe-58) displays stronger negative deflection and ha s a higher balance energy, which are qualitatively in agreement with t he experimental data. Furthermore, the effects of the isospin-dependen t symmetry energy and nucleon-nucleon cross sections on collective flo w are studied. [S0556-2813(98)07010-1].