Fg. Wang et al., THE CRITICAL-POINTS OF A GENERALIZED MIXED SPIN MODEL WITH FREE FERMION APPROXIMATION, Communications in Theoretical Physics, 22(2), 1994, pp. 145-150
A generalized mixed spin model with anisotropic interactions is consid
ered on the union jack lattice. We find that the model is equivalent t
o a free fermion model. The critical temperature is obtained. In speci
al cases, we get the same results as exact solutions.