A Minimal description of morphological hierarchy in two-dimensional aggregates

TL;DR

This paper introduces a dimensionless parameter to describe morphological transitions in 2D aggregates influenced by competing forces, providing a unified framework for understanding their structural evolution.

Contribution

It proposes a minimal, dimensionless description of 2D aggregate morphologies based on a new parameter $ extLambda$, linking structural transitions to measurable thermodynamic quantities.

Findings

Identification of a dimensionless parameter $ extLambda$ that characterizes morphology.

Observation of structural transitions from non-compact to percolated structures.

Data collapse among $S_2$, $B_2^*$, and $ extLambda$, supporting the minimal description.

Abstract

A dimensionless parameter $\Lambda$ is proposed to describe a hierarchy of morphologies in two-dimensional (2D) aggregates formed due to varying competition between short-range attraction and long-range repul- sion. Structural transitions from finite non-compact to compact to percolated structures are observed in the configurations simulated by molecular dynamics at a constant temperature and density. Configurational randomness across the transition, measured by the two-body excess entropy $S_2$, exhibits data collapse with the average potential energy $\bar{\mathcal{E}}$ of the systems. Independent master curves are presented among $S_2$, the reduced second virial coefficient $B_2^*$ and $\Lambda$, justifying this minimal description. This work lays out a coherent basis for the study of 2D aggregate morphologies relevant to diverse nano- and bio-processes.