**Microscopic
DC-TDHF
study of heavy-ion potentials and fusion cross sections**,
V. E. Oberacker, *Vanderbilt
University, USA* − The
calculation of heavy-ion interaction potentials is of
fundamental importance
for the study of fusion reactions between stable and
neutron-rich nuclei, and
for the study of superheavy element production.

We
have
developed a new microscopic method to extract ion-ion potentials
directly
from the TDHF time-evolution of the nuclear system. The only input is the
effective NN interaction
(Skyrme), there are no adjustable parameters.

In
the
DC-TDHF approach [1] the TDHF time-evolution takes place with no
restrictions. At
certain times during
the evolution the instantaneous density is used to perform a
static
Hartree-Fock minimization while holding the neutron and proton
densities
constrained to be the corresponding instantaneous TDHF
densities. There is no
need to introduce constraining operators which assume that the
collective
motion is confined to the constrained phase space. Rather, we have a
self-organizing system which
selects its path following the microscopic dynamics.

Some
of
the effects included in DC-TDHF are: neck formation, mass
exchange, internal
excitations, deformation effects to all order, and nuclear
alignment for
deformed systems.

From
the
calculations, carried out on a 3-D lattice, we obtain heavy-ion
interaction
potentials, fusion/capture cross sections, dynamic excitation
energies E*(t)
during the collision, and pre-equilibrium photon emission due to
giant
resonances excitation in fusion reactions. The theory has been
applied to the
reactions ^{64}Ni+^{132}Sn [2], ^{64}Ni+^{64}Ni
[3],
^{16}O+^{208}Pb [4], ^{70}Zn+^{208}Pb
and ^{48}Ca+^{238}U
[5], and ^{132,124}Sn+^{96}Zr [6]. Very recent
calculations for
^{40,48}Ca+^{124,132}Sn fusion rections
(measured at HRIBF)
will be presented.

We
have
also developed a new method [7] to calculate the ion-ion
potential in
terms of building blocks which we refer to as ”single-particle
interaction
potentials''. The
breakdown of the
ion-ion potential to the single-particle level shows which
states are driving
the system towards fusion (bonding states) and which states
resist fusion
(anti-bonding states).

[1]
A. S. Umar and V.
E. Oberacker, Phys. Rev. C **74**,
021601(R) (2006).

[2]
A. S. Umar and V.
E. Oberacker, Phys. Rev. C **76**,
014614 (2007).

[3]
A. S. Umar and V.
E. Oberacker, Phys. Rev. C **77**,
064605 (2008).

[4]
A. S. Umar and V.
E. Oberacker, Eur. Phys. J. A **39,**
243 (2009).

[5]
A. S. Umar, V. E.
Oberacker, J. A. Maruhn and P.-G.
Reinhard, Phys. Rev. C **81**,
064607 (2010).

[6]
V. E. Oberacker, A.
S. Umar, J. A. Maruhn and P.-G. Reinhard, Phys. Rev. C **82**, 034603 (2010).