The transverse Ising model: fermionic representation and the functional integral approach
W Wiethege, D Sherrington
The authors derive a functional integral representation for the partition function of the transverse Ising model. The spin operators are replaced by fermion operators and special care is taken to achieve complete equivalence of the spin model and the fermion model. They discuss several approximations for the functional integral and show that in a recent paper on spin glasses, where a similar method was used, the original spin model and the fermion model, which was obtained by replacing the spin operators by fermion operators, are not equivalent and have different critical temperatures.
Journal of Physics C Solid State Physics•Dec 20, 1986•13 citations