Vicsek Model

Parameters

Order Parameter

φ = |⟨v⟩|/v₀
η_c (critical noise)
Mean neighbors
Phase
θᵢ(t+1) = ⟨θ(t)⟩_r + ξ
ξ ~ Uniform[−ηπ, ηπ]
φ = (1/Nv₀)|Σvᵢ|
η_c ~ ρ^(1/2) (mean-field)
Phase transition at η_c: ordered→disordered
Particle Simulation
Order φ(t)
Phase Diagram ρ vs η