Microcanonical-ensemble computer simulation of the high-temperature expansion coefficients of the Helmholtz free-energy of a Square-well fluid

TL;DR

This paper employs the Microcanonical Ensemble simulation method to efficiently compute high-temperature expansion coefficients of the Helmholtz free energy for a Square-Well fluid, surpassing traditional methods in accuracy and scope.

Contribution

It introduces the MCE method for calculating perturbation terms of the Helmholtz free energy in Square-Well fluids, enabling the determination of multiple expansion terms more efficiently than standard approaches.

Findings

MCE method accurately computes the first six expansion terms.

Results cover attractive ranges from 1.1 to 1.8.

Semiempirical representation aids phase diagram accuracy.

Abstract

The Microcanonical Ensemble computer simulation method (MCE) is used to evaluate the perturbation terms $A_i$ of the Helmholtz free energy of a Square-Well (SW) fluid. The MCE method offers a very efficient and accurate procedure for the determination of perturbation terms of discrete-potential systems such as the SW fluid and surpass the standard NVT Canonical Ensemble Monte Carlo method, allowing the calculation of the first six expansion terms. Results are presented for the case of a SW potential with attractive ranges $1.1 \le \lambda \le 1.8$. Using semiempirical representation of the MCE values for $A_i$, we also discuss the accuracy in the determination of the phase diagram of this system.