Emergent Swarming States in Active Particles System with Opposite Anisotropic Interactions

From the organization of animal ocks to the emergence of swarming behav- iors in bacterial suspension, populations of motile organisms at all scales display coherent collective motion. Recent studies showed the anisotropic interaction between the active particles plays a key role on the phase behaviors. Here we investigate the collective behaviors of active Janus particles that experience an anisotropic interaction that is opposite to the active force by using Langevin dynamics simulations in two dimensional space. Interestingly, the system shows emergence of collective swarming states upon increasing the total area fraction of particles, which is not observed for systems without anisotropic interaction or activity. The threshold value of area fraction c decreases with particle ac- tivity or interaction strength. We have also performed basic kinetic analysis to reproduce the essential features of the simulation results. Our results demon- strate that anisotropic interactions at the individual level are sucient to set homogeneous active populations into stable directed motion.