Replica exchange Monte Carlo applied to Hard Spheres

TL;DR

This paper introduces a replica exchange Monte Carlo method that expands volume at constant pressure to efficiently sample hard sphere configurations and accurately determine their equation of state, including phase transitions.

Contribution

The novel approach applies volume expansion in replica exchange Monte Carlo to study hard spheres, capturing phase transitions in a single simulation.

Findings

Successfully reproduces the hard sphere equation of state

Captures the first-order fluid-solid transition

Agrees with previous computational results

Abstract

In this work a replica exchange Monte Carlo scheme which considers an extended isobaric-isothermal ensemble with respect to pressure is applied to study hard spheres (HS). The idea behind the proposal is expanding volume instead of increasing temperature to let crowded systems characterized by dominant repulsive interactions to unblock, and so, to produce sampling from disjoint configurations. The method produces, in a single parallel run, the complete HS equation of state. Thus, the first order fluid-solid transition is captured. The obtained results well agree with previous calculations. This approach seems particularly useful to treat purely entropy-driven systems such as hard body and non-additive hard mixtures, where temperature plays a trivial role.