  The computer simulation of many molecular processes is complicated by long
time scales caused by rare transitions between long-lived states. Here, we
propose a new approach to simulate such rare events, which combines transition
path sampling with enhanced exploration of configuration space. The method
relies on exchange moves between configuration and trajectory space, carried
out based on a generalized ensemble. This scheme substantially enhances the
efficiency of the transition path sampling simulations, particularly for
systems with multiple transition channels, and yields information on
thermodynamics, kinetics and reaction coordinates of molecular processes
without distorting their dynamics. The method is illustrated using the
isomerization of proline in the KPTP tetrapeptide.
