Can fast switching simulations beat conventional free energy calculation methods?
Christoph Dellago Jarzynski’s recent theorem relates equilibrium free energies to the statistics of work accumulated in irreversible transformations between ensembles. Fast switching simulations based on this theorem can be carried out with arbitrary switching rate promising inexpensive free energy estimation algorithms. Straightforward application of the fast switching method, however, is efficient only if the system is driven away from equilibrium only mildly thus requiring the generation of long non-equilibrium trajectories. The reason for this limitation lies in the distribution of work at fast switching rates: the values of work contributing most to the free energy are rarely sampled causing large statistical errors. By combining transition path sampling methods with biased sampling procedures one can focus on the trajectories carrying the largest contribution to the non-equilibrium averages. Here we discuss whether such biased fast switching methods can be more efficient than con
