---
abstract: 'A sampling procedure to compute exactly the rate of activated processes arising in systems at equilibrium or nonequilibrium steady state is presented. The procedure is a generalization of the method in \[A. Warmflash, P. Bhimalapuram, and A. R. Dinner, J. Chem. Phys. [**127**]{}, 154112 (2007); A. Dickson, A. Warmflash, and A. R. Dinner, J. Chem. Phys. [**130**]{}, 074104 (2009)\] in which one performs simulations restricted into cells by using a reinjection rule at the boundaries of the cells which is consistent with the exact probability fluxes through these boundaries. Our generalization uses results from transition path theory which indicate how to twist the dynamics to calculate reaction rates.'
author:
- 'Eric Vanden-Eijnden'
- Maddalena Venturoli
title: Exact rate calculations by trajectory parallelization and twisting
---

#### Introduction. {#introduction. .unnumbered}

The main objective of this work is to revisit and extend in scope the nonequilibrium sampling procedure to compute steady state probability distributions proposed in Refs. . Specifically, we show how this procedure can be modified to calculate exactly certain dynamical quantities such as the rate of reactions occurring in arbitrary equilibrium or nonequilibrium systems at statistical steady state. This is done by exploiting results of transition path theory 