Collective Motion of Self-Propelled Particles with Voter-Like Interactions

GABRIEL BAGLIETTO; FEDERICO VAZQUEZ

Buenos Aires

Encuentro; 1er Encuentro de Sociofísica; 2015

UBA

We study the collective motion of self-propelled particles with voter-like interactions. Each particle moves at a constant speed on a two- dimensional space and, in single step of the dynamics, it aligns its direction of motion with that of a randomly chosen neighboring particle. Directions are also perturbed by an external noise of amplitude η. We find that, in the absence of a noise η = 0, the system ultimately reaches full nematic order. However, in the thermodynamic limit, a very small amount of noise η > 0 is enough to keep the system totally disordered.Besides, the dynamics of ordering is much slower than in the standard Vicsek model, and is characterized by an order parameter φ that increases as φ ∼ t^1/2 for short times, and approaches exponentially fast to 1 for long times. Also, the mean convergence time to the fully ordered state is non-monotonic with the density of particles, due to the complex coevolution between the pattern of interactions and the diffusion of directional states.