The isospin effect of momentum-dependent interaction in heavy ion collisions

We introduce the isospin degree of freedom into the momentum-dependent interaction to obtain an isospin and momentum dependent interaction given in a form practically usable in isospin-dependent quantum molecular dynamics model. We investigate the isospin effect of momentum-dependent interaction on the observable in the intermediate-energy heavy ion collisions. It is found that momentum-dependent interactions with and without isospin dependence, lead to significant different predictions on the nuclear stopping ( momentum dissipation) and isospin fractionation ratio. In particular, the momentum-dependent interaction with the isospin degree of freedom induces the reduction for the strong dependence of isospin fractionation ratio on the symmetric potential. However, it does not change obviously the above feature for the isospin fractionation ratio as the good probe of symmetric potential respectively. The isospin dependence of momentum-dependent interaction is thus important for studying accurately the equation of state of isospin asymmetry nuclear matter.