Lane formation and crystallization of active matter in a narrow channel

The behavior of interacting active disks trapped by two planar hard walls is investigated. Motivated by earlier works, we employed active dynamics simulation in order to investigate the emergence of lanes of particles and their internal structure. Further we observed a correlation between the number of lanes formed and channel width. At first sight, larger channels favor the emergence of lanes with fluid-like bulk structure among them. We saw that, for a given packing fraction and wall separation, one realizes a better structural organization, very close to a triangular lattice, which was absent for other cases. We attributed the crystallization in the bulk to the repulsion from upper and bottom particles attached to the walls. The fluctuation of the total number of particles at the walls also is analyzed and its contribution for the lane formation and structure is considered.