Diffusion-Limited Cluster Aggregation: Impact of Rotational Diffusion

Abstract

Diffusion-limited cluster aggregation (DLCA) is a well established model for the formation of highly porous low-density nonequilibrium structures on the atomistic level. One of the main conclusions of the previous studies considering this model is that the rotational diffusion of aggregating clusters does not change their structure characterized by a universal fractal dimension of df = 1.7–1.8. In contradiction to this assumption, we demonstrate that the rotation movement of clusters significantly changes the structure of forming aggregates. The fractal dimension of the rotating clusters is lower than the one found in the standard DLCA model and decreases with the increasing ratio of rotational and translational diffusion constants Dr/Dt, which offers a possibility to tune the structures of the nanoparticle aggregates below the conventional DLCA fractal dimension limit.