Fourth virial coefficients of asymmetric nonadditive hard-disc mixtures

TL;DR

This paper calculates the fourth virial coefficient for asymmetric nonadditive hard-disk mixtures using Monte Carlo simulations across various size ratios and nonadditivities, comparing results with theoretical models and exploring implications for equations of state.

Contribution

It provides new numerical data for the fourth virial coefficient of asymmetric nonadditive hard-disk mixtures and assesses their use in improved equations of state.

Findings

Numerical results agree with some theoretical predictions.

Data useful for developing new equations of state.

Comparison with Monte Carlo simulations validates the approach.

Abstract

The fourth virial coefficient of asymmetric nonadditive binary mixtures of hard disks is computed with a standard Monte Carlo method. Wide ranges of size ratio ($0.05\leq q\leq 0.95$) and nonadditivity ($-0.5\leq \Delta\leq 0.5$) are covered. A comparison is made between the numerical results and those that follow from some theoretical developments. The possible use of these data in the derivation of new equations of state for these mixtures is illustrated by considering a rescaled virial expansion truncated to fourth order. The numerical results obtained using this equation of state are compared with Monte Carlo simulation data in the case of a size ratio $q=0.7$ and two nonadditivities $\Delta=\pm 0.2$.