Collective dynamics and pair-distribution function of active Brownian ellipsoids in two spatial dimensions

Abstract

While the collective dynamics of spherical active Brownian particles is relatively well understood by now, the much more complex dynamics of nonspherical active particles still raises interesting open questions. Previous work has shown that the dynamics of rod-like or ellipsoidal active particles can differ significantly from that of spherical ones. Here, we obtain the full state diagram of active Brownian ellipsoids in two spatial dimensions without hydrodynamic interactions depending on the Péclet number and packing density via computer simulations. The system is found to exhibit a rich state behavior that includes cluster formation, local polar order, polar flocks, and disordered states. Moreover, we obtain numerical results and an analytical representation for the pair-distribution function of active ellipsoids. This function provides useful quantitative insights into the collective behavior of active particles with lower symmetry and has potential applications in the development of predictive theoretical models.

The authors study the collective behavior of ellipsoidal active particles, which is richer and less understood than that of their spherical counterparts. They find a variety of states such as cluster formation, local polar order, polar flocks, and disordered states, and obtain an analytical expression for the pair-distribution function, which allows a quantitative characterization of the system’s state.