Dynamic Study on Fusion Reactions for Zr around Coulomb Barrier *

By using the updated improved Quantum Molecular Dynamics model in which a surface-symmetry potential term has been introduced for the first time, the excitation functions for fusion reactions of 40,48Ca+90,96Zr at energies around the Coulomb barrier have been studied. The experimental data of the fusion cross sections for 40Ca+90,96Zr have been reproduced remarkably well without introducing any new parameters. The fusion cross sections for the neutron-rich fusion reactions of 48Ca+90,96Zr around the Coulomb barrier are predicted to be enhanced compared with a non-neutron-rich fusion reaction. In order to clarify the mechanism of the enhancement of the fusion cross sections for neutron-rich nuclear fusions, we pay a great attention to study the dynamic lowering of the Coulomb barrier during a neck formation. The isospin effect on the barrier lowering is investigated. It is interesting that the *Email address: [email protected] †Email address: [email protected]