The structure of a fluid in the canonical and in the grand canonical ensembles

TL;DR

This paper investigates how the structure of fluids with long-range interactions differs between the canonical and grand canonical ensembles, highlighting the longstanding issue of ensemble inequivalence in Coulomb liquids and similar systems.

Contribution

It demonstrates that ensemble inequivalence affects many long-range fluids, extending the known phenomenon from Coulomb liquids to a broader class of systems.

Findings

Ensemble inequivalence impacts the structural description of long-range fluids.

Canonical and grand canonical ensembles yield different structural properties.

The results suggest the need to carefully choose ensembles in theoretical studies of such fluids.

Abstract

The ensemble inequivalence in a (unscreened) Coulomb liquid has been known since the years 1960s. The structure described by the canonical ensemble and the grand canonical ensemble are not equivalent. We show that this fact also affects many long range fluid.