Collective behaviors of self-propelled particles with tunable alignment angles

TL;DR

This paper introduces a new active matter model with tunable alignment angles, revealing how frustration affects collective behaviors and destabilizes nematic order, supported by simulations and stability analysis.

Contribution

It extends the nematic alignment rule to tunable angles, exploring the resulting collective phenomena and stability properties in self-propelled particle systems.

Findings

Anti-parallel bands emerge at intermediate alignment angles.

Frustration destabilizes homogeneous nematic order.

Qualitative agreement between microscopic simulations and continuum analysis.

Abstract

We present a novel aligning active matter model by extending the nematic alignment rule in self-propelled rods to tunable alignment angles, as represented by collision of cone-shaped particles. Non-vanishing alignment angles introduce frustration in the many-body interactions, and we investigate its effect on the collective behavior of the system. Through numerical simulations of an agent-based microscopic model, we found that the system exhibits distinct phenomenology compared to the original self-propelled rods. In particular, anti-parallel bands are observed in an intermediate parameter range. The linear stability analysis of the continuum description derived from the Boltzmann approach demonstrates qualitative consistency with the microscopic model, while frustration due to many-body interactions in the latter destabilizes homogeneous nematic order over a wide range of the alignment angle.