Bidimensional fluid system with competing interactions

TL;DR

This study investigates pattern formation in two-dimensional systems with competing attractive and repulsive interactions, comparing spontaneous and externally induced patterns, and evaluates Monte Carlo methods and theoretical predictions for these phenomena.

Contribution

It introduces detailed Monte Carlo simulations and theoretical analyses for pattern formation in bidimensional systems with competing interactions, highlighting the effectiveness of Parallel Tempering.

Findings

Parallel Tempering improves sampling efficiency

Strong external fields induce pronounced pattern formation

System response exceeds that of Lennard-Jones fluids

Abstract

In this paper we present a study of pattern formation in bidimensional systems with competing short-range attractive and long-range repulsive interactions. The interaction parameters are chosen in such a way to analyse two different situations: the spontaneous pattern formation due to the presence of strong competing interactions on different length scales and the pattern formation as a response to an external modulating potential when the system is close to its Lifshitz point. We compare different Monte Carlo techniques showing that Parallel Tempering technique represents a promising approach to study such systems and we present detailed results for the specific heat and the structural properties. We also present random phase approximation predictions about the spontaneous pattern formation (or microphase separation), as well as linear response theory predictions about the induced pattern formation due to the presence of an external modulating field. In particular we observe that the response of our systems to external fields is much stronger compared to the response of a Lennard-Jones fluid.