Two-Spin Ising Correlations
Inspect interaction-driven spin correlations and the role of degenerate ground states.
Free theory articleInspect interaction-driven spin correlations and the role of degenerate ground states.
Concept & interpretation
The Ising model describes interacting binary spins. In a simple two-spin system, the full partition function and resulting thermodynamic observables can be calculated exactly without approximations.
Exploring phase space and zero-temperature limit
To see how interactions affect the system, open the Two-Spin Ising Correlations module and try the following:
- Set Coupling J to -1 (antiferromagnetic) and Field h to 0. Notice the ground-state degeneracy is 2, and magnetization per spin is 0.
- Change Temperature to 0. The Heat capacity drops to 0, and Total susceptibility becomes exactly 0 (divergent if fluctuations remain, but here var(M)=0). Entropy reflects the log of the degeneracy.
- Set Field h to 1 and observe the shift in probabilities towards the state aligned with the field.