Driven Widom-Rowlinson lattice gas

TL;DR

This paper investigates how applying a drive affects the phase behavior and domain structures in the Widom-Rowlinson lattice gas, revealing novel phenomena like multiple stripe formation and rough interfaces, distinct from driven Ising models.

Contribution

It introduces a detailed analysis of driven Widom-Rowlinson lattice gas, highlighting new features such as kink singularities, non-vanishing wavevector maxima, and multistripe states, expanding understanding of nonequilibrium phase transitions.

Findings

Discovery of multiple striped domains perpendicular to the drive

Identification of structure factors with kink singularities and maxima at finite wavevectors

Observation that interfaces remain rough despite driving, contrasting with KLS model

Abstract

In the Widom-Rowlinson lattice gas, two particle species (A, B) diffuse freely via particle-hole exchange, subject to both on-site exclusion and prohibition of A-B nearest-neighbor pairs. As an athermal system, the overall densities are the only control parameters. As the densities increase, an entropically driven phase transition occurs, leading to ordered states with A- and B-rich domains separated by hole-rich interfaces. Using Monte Carlo simulations, we analyze the effect of imposing a drive on this system, biasing particle moves along one direction. Our study parallels that for a driven Ising lattice gas -- the Katz-Lebowitz-Spohn (KLS) model, which displays atypical collective behavior, e.g., structure factors with discontinuity singularities and ordered states with domains only parallel to the drive. Here, other novel features emerge, including structure factors with kink singularities (best fitted to |q|), maxima at non-vanishing wavevector values, oscillating correlation functions, and ordering into multiple striped domains perpendicular to the drive, with a preferred wavelength depending on density and drive intensity. Moreover, the (hole-rich) interfaces between the domains are statistically rough (whether driven or not), in sharp contrast with those in the KLS model, in which the drive suppresses interfacial roughness. Defining a novel order parameter (to account for the emergence of multistripe states), we map out the phase diagram in the density-drive plane and present preliminary evidence for a critical phase in this driven lattice gas.