Some computational aspects of Jarzynki's non-equilbrium work theorem
Prof. Christoph Dellago
Université de Vienne
Lundi 19/05/2008, 14:15
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
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 work distribution at fast switching rates: the values of work contributing most to the free energy are rarely sampled causing large statistical errors. Here, I will discuss several computational strategies, including large time step integration and bias path sampling, to circumvent this problem. The algorithms will be illustrated using the calculation of the chemical potential of simple fluid and the stretching of a small polypeptide as examples.