Nonequilibrium steady states in contact: Approximate thermodynamic structure and zero-th law for driven lattice gases

TL;DR

This paper investigates driven lattice gases to identify an intensive thermodynamic variable governing nonequilibrium steady-state contact, revealing approximate thermodynamic laws and deviations at higher densities due to complex interactions.

Contribution

It demonstrates the existence of an approximate thermodynamic structure and zero-th law in driven lattice gases, highlighting the effects of contact dynamics and correlations.

Findings

Systems obey zero-th law and fluctuation-response relation well at low densities.

Deviations from thermodynamic laws occur at higher densities.

Long-range correlations influence contact dynamics and thermodynamic behavior.

Abstract

We explore driven lattice gases for the existence of an intensive thermodynamic variable which could determine "equilibration" between two nonequilibrium steady-state systems kept in weak contact. In simulations, we find that these systems satisfy surprisingly simple thermodynamic laws, such as the zero-th law and the fluctuation-response relation between the particle-number fluctuation and the corresponding susceptibility remarkably well. However at higher densities, small but observable deviations from these laws occur due to nontrivial contact dynamics and the presence of long-range spatial correlations.