Effects of diabaticity on fusion of heavy nuclei in the dinuclear model ...

the neck coordinate ε and <strong>of</strong> the mass asymmetry η were calculated for the entrance phase <strong>of</strong>
collisions between spherical heavy nuclei. The effect <strong>of</strong> the deformation <strong>of</strong> the nuclei and <strong>of</strong> the
temperature on the diabatic potential energy as a function <strong>of</strong> the elongation λ was analysed.
In a diabatic description the nucleons do not occupy the lowest free single-particle levels as
in the adiabatic case, but remain in the diabatic levels during the collective motion <strong>of</strong> the
nuclear system. As a result, the diabatic potential energy surface is raised with respect to
the adiabatic potential energy surface and new potential barriers for collective variables may
appear. From the study <strong>of</strong> the diabatic single-particle spectrum, we obtained that the diabatic
effects for the motion <strong>of</strong> the system in λ and in ε are already important for relatively small
excitation energies <strong>of</strong> 6—14 MeV. Diabatic TCSM levels do not show avoided level crossings.
Avoided level crossings can be removed from the adiabatic TCSM by eliminating the symmetry-
violating parts from the adiabatic Hamiltonian <strong>of</strong> the TCSM. Since the diabatic effects are
small near the touching <strong>of</strong> the nuclei, they are not important for the potential <strong>of</strong> the dinuclear
system as a function <strong>of</strong> the mass asymmetry η at the touching configuration <strong>of</strong> the nuclei.
The isotopic dependence <strong>of</strong> the potential as a function <strong>of</strong> the mass asymmetry coordinate η
at the touching configuration <strong>of</strong> the nuclei calculated within the adiabatic TCSM using the
Strutinsky method was studied for various heavy dinuclear systems. Moreover, this potential
was compared with the potentials calculated with a phenomenological method and with another
alternative microscopical method. The phenomenological method uses the binding energy <strong>of</strong>
the nuclei and the nucleus-nucleus potential which includes the Coulomb and nuclear terms.
The nuclear part <strong>of</strong> the nucleus-nucleus potential is calculated using a double-folding procedure.
With the alternative microscopical method, the potential energy is calculated using the rate <strong>of</strong>
probability <strong>of</strong> nucleon transfer between the nuclei <strong>of</strong> the dinuclear system.
Mass parameters as a function <strong>of</strong> the elongation λ, the neck coordinate ε, the mass asym-
metry η and <strong>of</strong> the deformation β i for heavy dinuclear systems were evaluated in the TCSM.
Formulas for the masses are derived within the linear response theory by taking into account the
fluctuation-dissipation theorem and the width <strong>of</strong> single particle states, and by other methods
as Fermi’s golden rule and a spectral smoothing in the mean—field cranking formula.
In order to study whether the fusion is possible in the elongation coordinate λ, we considered
the transition from the diabatic potential to the adiabatic one in the motion <strong>of</strong> the system in
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