Competing effects of rotational diffusivity and activity on finite-sized clusters

Abstract

Colloidal particles interacting via short-range attraction and long-range repulsion are known to stabilize finite-sized clusters under equilibrium conditions. In this work, the effect of self-propulsion speed (activity) and rotational diffusivity (D r) on the phase behavior of such particles is investigated using Brownian dynamics simulations. The system exhibits rich phase behavior consisting of clusters of different kinds. The cluster size varies non-monotonically with activity: increasing first and decreasing at higher activity, thus driving cluster-to-fluid phase transition. Rotational diffusivity also facilitates the formation of clusters. Larger clusters could be stabilized at low D r values while at high D r values, clusters are stable even at higher activities. The analysis of the static structure factor of the system confirms that rotational diffusivity delays the cluster-to-fluid transition driven by activity.