Eur. Phys. J. B 64, 331-340 (2008)
https://doi.org/10.1140/epjb/e2008-00254-2

Nonequilibrium work relations: foundations and applications

Department of Chemistry and Biochemistry, and Institute for Physical Science and Technology University of Maryland, College Park, MD 20742 USA

Corresponding author: ^a cjarzyns@umd.edu

Received: 2 September 2007
Revised: 21 March 2008
Published online: 3 July 2008

Abstract

When a macroscopic system in contact with a heat reservoir is driven away from equilibrium, the second law of thermodynamics places a strict bound on the amount of work performed on the system. With a microscopic system the situation is more subtle, as thermal fluctuations give rise to a statistical distribution of work values. In recent years it has been realized that such distributions encode surprisingly more information than one might expect from traditional thermodynamic arguments. I will discuss a number of exact results that relate equilibrium properties of the system, in particular free energy differences, to the fluctuations in the work performed during such a nonequilibrium process. I will describe the theoretical foundations of these relations, connections with irreversibility and the second law of thermodynamics, and potential experimental and computational applications.