An efficient method to reconstruct free energy profiles for diffusive processes in transition interface sampling and forward flux sampling simulations.

Abstract

We propose a Reweighted Partial Path (RPP) method to compute free energy profiles for diffusive processes in single Transition Interface Sampling (TIS) or Forward Flux Sampling (FFS) simulations. The method employs a partial path reweighting strategy, based on the memory loss assumption for diffusive systems, to derive the equilibrium distribution of states along a chosen order parameter from TIS or FFS trajectories. No additional calculations such as reverse TIS or umbrella sampling are required. The application of the RPP method is demonstrated by calculating the nucleation free energy of early-stage Cu precipitates in a dilute Fe-Cu alloy.