The effect of attractions on the local structure of liquids and colloidal fluids

TL;DR

This study investigates how attractions influence the local structure of liquids and colloidal suspensions using pair correlation functions and a novel topological method, revealing contrasting effects based on attraction range.

Contribution

It introduces a topological approach to analyze local structures in liquids, demonstrating how attraction range affects clustering and structure formation.

Findings

Attractions increase larger cluster formation in Lennard-Jones liquids.

Short-ranged attractions reduce clustering despite similar pair correlations.

Weakly interacting systems show similar structures in pair and topological analyses.

Abstract

We revisit the role of attractions in liquids and apply these concepts to colloidal suspensions. Two means are used to investigate the structure; the pair correlation function and a recently developed topological method. The latter identifies structures topologically equivalent to ground state clusters formed by isolated groups of 5 < m < 13 particles, which are specific to the system under consideration. Our topological methodology shows that, in the case of Lennard-Jones, the addition of attractions increases the system's ability to form larger (m>8) clusters, although pair-correlation functions are almost identical. Conversely, in the case of short-ranged attractions, pair correlation functions show a significant response to adding attraction, while the liquid structure exhibits a strong decrease in clustering upon adding attractions. Finally, a compressed, weakly interacting system shows a similar pair structure and topology.