q-state model · 1st vs 2nd order transition · Monte Carlo
Parameters
Measurements
Energy/site—
Magnetization—
Step0
q≤4: 2nd order—
Potts model: generalization of Ising (q=2) to q spin states; neighbors prefer the same state with energy -J·δ(s_i,s_j). Critical behavior: q≤4 (in 2D) gives a second-order (continuous) transition; q≥5 gives a first-order (discontinuous) transition with latent heat. Critical temperature: k_BT_c/J = 1/ln(1+√q). Monte Carlo via Metropolis algorithm.