Hey all, I've got a Hamiltonian of the form [tex] H = \omega (\sigma_z^1 - \sigma_z^2) + J \sigma_z^1 \sigma_z^2 [/tex] where [itex] \omega [/itex] is a frequency ( I think), J is the indirect dipole-dipole coupling, and [itex] \sigma_z^i [/itex] is the Pauli Z operator on the ith particle. Does anybody know what this Hamiltonian represents? Where it's used? Or values for [itex] \omega, J [/itex]? I can look up J coupling easily enough given that I randomly choose two interacting particles/molecules, but I'm really uncertain as to what [itex] \omega [/itex] represents in this case and what values it should take.