  A numerical simulation method, based on Dang et al.'s self-consistent theory
of large-amplitude collective motion, for rare transition events is presented.
The method provides a one-dimensional pathway without knowledge of the final
configuration, which includes a dynamical effect caused by not only a potential
but also kinetic term. Although it is difficult to apply the molecular dynamics
simulation to a narrow-gate potential, the method presented is applicable to
the case. A toy model with a high-energy barrier and/or the narrow gate shows
that while the Dang et al. treatment is unstable for a changing of model
parameters, our method stable for it.
