Jarzynski equality

The Jarzynski equality is also known as the work relation or non-equilibrium work relation. According to it, the equilibrium free energy of a process, $\Delta G$, can be reconstructed by averaging the external work, $W$, performed in many nonequilibrium realizations of the process:

$\exp \left({\frac {-\Delta G}{k_{B}T}}\right)=\left\langle \exp \left({\frac {-W}{k_{B}T}}\right)\right\rangle$

References

1. C. Jarzynski "Nonequilibrium Equality for Free Energy Differences", Physical Review Letters 78 2690-2693 (1997)
2. E. G. D. Cohen; D. Mauzerall "The Jarzynski equality and the Boltzmann factor", Molecular Physics 103 pp. 2923 - 2926 (2005)