  In this work, we introduce a new method to reduce the microscopic mean-field
theory to a classical macroscopic dynamics during the initial stage of fusion
reactions. We show that TDHF (Time-dependent Hartree-Fock) could be a useful
tool to gain information on fusion barriers as well as on one-body dissipation
effects. We apply the mean-field theory to the case of head-on reaction between
$^{16}$O and $^{16,22,24,28}$O in order to quantify the effect of neutron skin
on fusion. We show that the determination of fusion barrier requires, in
addition to a precise knowledge of the relative distance between the center of
mass of the two fusing nuclei, the introduction of an additional collective
coordinate that explicitly breaks the neutron-proton symmetry. In this context,
we estimate the position, height and diffuseness of the barrier as well as the
one-body friction and show that a global enhancement of the fusion
cross-section is expected in neutron rich nuclei.
