For submission to Molecular Physics

Calculation of free-energy differences using exponential-work averaging methods is examined, focusing on the amount of sampling required to converge to an accurate result. We review prior research that has demonstrated that the necessary amount of sampling scales exponentially with the dissipated work associated with the reverse trajectory. We demonstrate the result through a pedagogical application to a model process involving adiabatic compression and expansion of a gas. Key words: molecular simulation; free-energy perturbation; non-equilibrium wor