Orientational ordering of active nematics confined to a 2D nanoscopic ring-shaped cavity

Abstract

We performed molecular dynamics simulations of model nonchiral and chiral active nematics confined to a two-dimensional nanoscopic ring-shaped region under both radial and tangential anchoring boundary conditions. These active nematics are composed of elongated particles which interact with each other through isotropic Lennard-Jones and anisotropic Maier-Saupe-like potentials. In addition, nonchiral particle’s terminal appendage emits a jet of some substance generated by a certain internal chemical reaction, whereas chiral particles have an analogous lateral one. As a result, nonchiral particles are exposed to an additional reactive self-propelled force directed along their long axes, and chiral particles are exposed to both the reactive self-propelled force and torque that provides both an additional translational movement of particles and a self-rotation with respect to their geometric centers. The nonchiral active nematics presents an orientational order similar to that formed by the passive (without the self-propelled force) ones within the same ring-shaped region. In contrast, the chiral nematics exhibits significantly different orientational order from those observed by passive ones. In addition, when the chirality of active nematic particles is sufficiently strong, the orientational order within the ring-shaped region undergoes substantial time oscillations.