Relaxation of the energy of the two-dimensional Ising model in the absence of an external constant magnetic field

The nonequilibrium statistical operator method is used to derive a kinetic equation for the energy of the $s=\frac12$ Ising model. Explicit solutions of this equation are obtained for different ratios of the temperature of the thermal bath and the phase transition temperature of the spin system. In particular, energy relaxation in the critical region is studied. The influence of the lattice geometry and the form of the interaction between the spin system and the thermal bath on the relaxation properties of the model is considered.