As part of an assignment for this course, I looked at the model introduced in Vicsek's 1995 paper . A draft of the report for this can be found here . For interest, I also breifly looked at the symettry breaking for systems with larger numbers of particles, as a initial configuration of particles with random positions and directions interact to select a globally prefered direction of motion. These are included for different particle numbers: 2500, 5000, 5000, 10000, 25000.
 Vicsek, et al., "Novel Type of Phase Transition in a System of Self Driven Particles, Phys. Rev. Lett. 75:1226, 1995.