Free energy of the random Ising model in terms of the magnetizations of sites

The free energy in the pair approximation of the cluster variation method is given in terms of the magnetizations of sites for the random Ising model. For a number of samples of the random-bond Ising model with nearest-neighbour interactions of +J and -J, on the square lattice, search is made of the configuration which gives the lowest free energy. It is concluded that the spin-glass state is the state which gives the lowest free energy in the pair approximation for certain values of temperature and probabilities of J and -J.