Dual thermodynamic ensembles, relative entropies, and excess free energy
Statistical Mechanics
2026-02-18 v1
Abstract
It has long been known that the relative entropy of a non-equilibrium ensemble to the corresponding equilibrium ensemble is the excess free energy. We show that the reverse relative entropy also has a thermodynamic interpretation: it is the excess free energy of a dual ensemble in which the roles of energy and entropy are interchanged.
Keywords
Cite
@article{arxiv.2602.15392,
title = {Dual thermodynamic ensembles, relative entropies, and excess free energy},
author = {Gavin E. Crooks},
journal= {arXiv preprint arXiv:2602.15392},
year = {2026}
}