  The time-dependent transmission coefficient for the generalized Kramers
problem with exponential memory friction has recently been calculated by Kohen
and Tannor [D. Kohen and D. J. Tannor, J. Chem. Phys. Vol. 103, 6013 (1995)]
using a procedure based on the method of reactive flux and the phase space
distribution function. Their analysis is restricted to the high friction regime
or diffusion-limited regime. We recently developed a complementary theory for
the low-friction energy-diffusion-limited regime in the Markovian limit [Sancho
et al., cond-mat/9806001, to appear in J. Chem. Phys.]. Here we generalize our
method to the case of an exponential dissipative memory kernel. We test our
results, as well as those of Kohen and Tannor, against numerical simulations.
