Long-Range Order of the Site-Random Spin Glass Model

The site-random Ising spin glass model is investigated. We find a rigorous symmetry for the SG correlation and the free energy, which provides some restrictions in the phase diagram. Using the defect energies calculated by the numerical transfer matrix method, we obtain evidence for the existence of the SG phase in the two-dimensional Ising system. We suggest that the transitions from the FM and the AF phases in the ground state in this model can be explained by the percolated-cluster picture, which is quite different from the frustration picture in the conventional $\pm J$ model.