  From a variety of long simulations of all-atom butane using both stochastic
and fully-solved molecular dynamics, we have uncovered striking generic
behavior which also occurs in one-dimensional systems. We find an apparently
universal distribution of transition event durations, as well as a
characteristic speed profile along the reaction coordinate. An approximate
analytic distribution of event durations, derived from a one-dimensional model,
correctly predicts the asymptotic behavior of the universal distribution for
both short and long durations.
