Critical Point Field Mixing in an Asymmetric Lattice Gas Model

TL;DR

This study investigates how field mixing affects the critical behavior of an asymmetric lattice gas model using Monte Carlo simulations, confirming theoretical predictions and providing a method to measure field mixing parameters.

Contribution

It demonstrates the impact of particle-hole asymmetry on critical density distributions and validates the mixed-field finite-size-scaling theory through simulation results.

Findings

Density distributions show antisymmetric corrections due to field mixing.

Functional form of corrections matches theoretical predictions.

A new computational method accurately measures field mixing parameters.

Abstract

The field mixing that manifests broken particle-hole symmetry is studied for a 2-D asymmetric lattice gas model having tunable field mixing properties. Monte Carlo simulations within the grand canonical ensemble are used to obtain the critical density distribution for different degrees of particle-hole asymmetry. Except in the special case when this asymmetry vanishes, the density distributions exhibit an antisymmetric correction to the limiting scale-invariant form. The presence of this correction reflects the mixing of the critical energy density into the ordering operator. Its functional form is found to be in excellent agreement with that predicted by the mixed-field finite-size-scaling theory of Bruce and Wilding. A computational procedure for measuring the significant field mixing parameter is also described, and its accuracy gauged by comparing the results with exact values obtained analytically.