  Collective reaction paths for fusion reactions, $^{16}$O+$\alpha$
$\rightarrow$ $^{20}$Ne and $^{16}$O+$^{16}$O $\rightarrow$ $^{32}$S, are
microscopically determined, on the basis of the adiabatic self-consistent
collective coordinate (ASCC) method. The collective path is maximally decoupled
from other intrinsic degrees of freedom. The reaction paths turn out to deviate
from those obtained with standard mean-field calculations with constraints on
quadrupole and octupole moments. The potentials and inertial masses defined in
the ASCC method are calculated along the reaction paths. The sub-barrier fusion
cross sections are calculated for these systems. Inertial mass inside the
Coulomb barrier may have a significant influence on the fusion cross section at
the deep sub-barrier energy.
