2D Ising Model at Criticality

Metropolis algorithm on a 64×64 spin lattice. T_c = 2/ln(1+√2) ≈ 2.269 (Onsager 1944). Diverging specific heat and susceptibility signal the second-order phase transition.

Temperature

T (J/k_B)2.27

T_c ≈ 2.269 ← critical point

Observables

Magnetization |m|—

Energy E/N—

Susceptibility χ—

Specific heat C—

Sweeps0

Speed

Sweeps/frame5

Susceptibility vs T

Peak at T_c indicates phase transition