Discontinuous percolation transitions in real physical systems

TL;DR

This paper investigates discontinuous percolation transitions in physical systems, specifically in the sol-gel transition modeled by diffusion-limited cluster aggregation, revealing how cluster mobility affects the abruptness of the transition.

Contribution

It demonstrates how cluster mobility influences discontinuous percolation transitions and identifies a tricritical point using an asymmetric Smoluchowski equation.

Findings

Discontinuous PT occurs when cluster mobility decreases with size.

Giant cluster size jumps drastically near the percolation threshold.

Tricritical behavior is characterized by controlling the mobility parameter ta.

Abstract

We study discontinuous percolation transitions (PT) in the diffusion-limited cluster aggregation model of the sol-gel transition as an example of real physical systems, in which the number of aggregation events is regarded as the number of bonds occupied in the system. When particles are Brownian, in which cluster velocity depends on cluster size as $v_s \sim s^{\eta}$ with $\eta=-0.5$, a larger cluster has less probability to collide with other clusters because of its smaller mobility. Thus, the cluster is effectively more suppressed in growth of its size. Then the giant cluster size increases drastically by merging those suppressed clusters near the percolation threshold, exhibiting a discontinuous PT. We also study the tricritical behavior by controlling the parameter $\eta$, and the tricritical point is determined by introducing an asymmetric Smoluchowski equation.