Dynamic potential barrier in the entrance phase of heavy-ion fusion reactions

Based on the improved quantum molecular-dynamics (ImQMD) model, the incident energy dependence of dynamic potential barriers is investigated in the entrance channel of fusion reactions. The height of the dynamic barrier increases with the incident energy at energies around the Coulomb barrier. The calculated lowest dynamic barrier approaches to the adiabatic barrier, while the highest one goes up to the sudden potential barrier. To understand the energy dependence of the dynamical barrier we study the neck formation and shape evolution of the system which causes the dynamic lowering of the barrier.