# Ising model for spins

by aaaa202
Tags: ising, model, spins
 P: 180 The average $\langle S_j^z \rangle$ is certainly changed by the external magnetic field - consider the extreme case with an antiferromagnetic $J$ and a strong field along some axis. This will change the mean field from zero in the case of no field to its maximal value in the case of a strong field. There are different mean fields for different Hamiltonians, if you will.