The XY model generalizes this model, so the sites can take on any values on the unit circle. For 10 points each:
[10m] Identify this model in which each site can take on a value of either plus one or minus one. Lars Onsanger solved this model in two dimensions.
ANSWER: Ising model
[10h] The states of this generalization of the Ising model can take are uniformly distributed on the unit circle. The Hamiltonian of this model is negative J times the summation of Kronecker deltas of all sites.
ANSWER: Potts model [or Askin-Teller model]
[10e] The lattice sites of both the Potts model and the Ising model can be taken as particles with this quantity. This intrinsic form of angular momentum correspond to the fourth quantum number.
ANSWER: spin
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