Nonequilibrium work energy relation for non-Hamiltonian dynamics

TL;DR

This paper generalizes the Jarzynski equality to non-Hamiltonian dynamics, enabling free energy calculations in systems with active matter, feedback, or simulation, regardless of the specific dynamics used.

Contribution

It introduces a universal relation that links nonequilibrium work to free energy differences for non-Hamiltonian systems, broadening the scope of free energy estimation methods.

Findings

Allows free energy calculation with arbitrary dynamics

Generalizes Jarzynski equality to non-Hamiltonian systems

Facilitates new techniques for free energy estimation

Abstract

Recent years have witnessed major advances in our understanding of nonequilibrium processes. The Jarzynski equality, for example, provides a link between equilibrium free energy differences and finite-time, nonequilibrium dynamics. We propose a generalization of this relation to non-Hamiltonian dynamics, relevant for active matter systems, continuous feedback, and computer simulation. Surprisingly, this relation allows us to calculate the free energy difference between the desired initial and final equilibrium states using arbitrary dynamics. As a practical matter, this dissociation between the dynamics and the initial and final states promises to facilitate a range of techniques for free energy estimation in a single, universal expression.