| dc.description.abstract | Active matter exhibits various non-equilibrium emergence behaviors. The shape of active matter individual particles is critical for the local interaction that determines the global emergence behaviors. Unlike spherical particles, rod- shaped particles show strong particle-particle alignment by simple volume exclu- sion. Therefore, active Brownian rods (ABR) can form biomimetic, turbulence, swarming, and jamming states. The current research of two-dimensional ABR focus on collective motion, and little is known about the dynamics. From the experimental observation of jamming dynamics in bacterial swarming, we found that the active force balance is critical for jamming. Inspired by this finding, we designed a tetragonal pseudo-crystal (TPC) that unit cells with three active rods crisscrossed orthogonally. We then used LAMMPS to perform Brownian dynamic simulation to study the dynamics of the active pseudo-crystal.
We found that the tetratic order and crystal stability are sensitive to the packing ratio and the active force. At a lower packing ratio or more vital active force, the TPC can melt into a turbulence state. On the other hand, the TPC can maintain the tetratic order at a high packing ratio even at a highly active force. Interestingly, there are long-living ordered intermediate states that the system contains few defects. By studying the dislocations of intermediate states of TPC, we reveal that the shear slipping events between ABR induce the melting process. Also, we found that the role of packing ratio and active force of ABR have different effects on deformation and melting dynamics in our two-dimensional ABR system. This work provides a new direction of active matter research on the Pseudo-crystal. | en_US |