LOW-TEMPERATURE PHASE OF THE 3-STATE ANTIFERROMAGNETIC POTTS-MODEL ONTHE SIMPLE-CUBIC LATTICE

The three-state antiferromagnetic Potts model on the simple-cubic latt ice is investigated using the cluster variation method in the cube and the star-cube approximations. The broken-sublattice-symmetry phase is found to be stable in the whole low-temperature region, contrary to p revious results obtained using a modified cluster variation method. Th e tiny free-energy difference between the broken-sublattice-symmetry a nd the permutationally-symmetric sublattice phases is calculated in th e two approximations and turns out to be smaller in the (more accurate ) star-cube approximation than in the cube one.