  Background: Multinucleon transfer (MNT) and quasifission (QF) processes are
dominant processes in low-energy collisions of two heavy nuclei. They are
expected to be useful to produce neutron-rich unstable nuclei. Nuclear dynamics
leading to these processes depends sensitively on nuclear properties such as
deformation and shell structure. Purpose: We elucidate reaction mechanisms of
MNT and QF processes involving heavy deformed nuclei, making detailed
comparisons between microscopic time-dependent Hartree-Fock (TDHF) calculations
and measurements for the $^{64}$Ni+$^{238}$U reaction. Methods:
Three-dimensional Skyrme-TDHF calculations are performed. Particle-number
projection method is used to evaluate MNT cross sections from the TDHF wave
function after collision. Results: Fragment masses, total kinetic energy (TKE),
scattering angle, contact time, and MNT cross sections are investigated for the
$^{64}$Ni+$^{238}$U reaction. They show reasonable agreements with
measurements. At small impact parameters, collision dynamics depends
sensitively on the orientation of deformed $^{238}$U. In tip (side) collisions,
we find a larger (smaller) TKE and a shorter (longer) contact time. In tip
collisions, we find a strong influence of quantum shells around $^{208}$Pb.
Conclusions: It is confirmed that the TDHF calculations reasonably describe
both MNT and QF processes in the $^{64}$Ni+$^{238}$U reaction. Analyses of this
system indicates the significance of the nuclear structure effects such as
deformation and quantum shells in nuclear reaction dynamics at low energies.
