"Simulation of reaction currents"
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Atypical, rare trajectories of dynamical systems are
important: they are often the paths for chemical reactions, the haven of
(relative) stability of planetary systems, the rogue waves that are
detected in oil platforms, the structures that are responsible for
intermittency in a turbulent liquid, the active regions that allow a
supercooled liquid to flow... Simulating them in an efficient,
accelerated way, is in fact quite simple.
I will review a computational technique to study such rare events in
both stochastic and Hamiltonian systems. The method is based on the
evolution of a family of copies of the system which are replicated or
killed in such a way as to favor the realization of the atypical
trajectories.
For the case of chemical reactions, using the `benchmark' example of a
molecule of 38 particles interacting through a Lennard-Jones potential,
I will show how the passages between different configurations may be
studied efficiently with this method.