  Using the random matrix model, we discuss the effect of couplings to
non-collective states on the penetrability of a one dimensional potential
barrier. We show that these non-collective excitations hinder the penetrability
and thus smear the barrier distribution at energies above the barrier, while
they do not affect significantly the penetrability at deep subbarrier energies.
The energy dependence of the Q-value distribution obtained with this model is
also discussed.
