Approximate calculation of the ground-state energy for Potts spin-glass models.

We consider the q-state Potts spin-glass model, with quenched couplings taking two different values only. As an approximation for this model a proper generalization of the random energy model is derived. Formulas of the resulting diluted generalized random energy model (DGREM) are applied to calculate the ground-state energy for the two-dimensional Potts spin-glass model. The semianalytical results are compared with numerical determinations of the ground-state energy, using multicanonical, random cost, and simulated annealing techniques.