Complex-temperature phase diagrams for the q-state Potts model on self-dual families of graphs and the nature of the q→∞ limit

Exact calculations of the Potts model partition function Z(G,q,v) on self-dual strip graphs G of the square lattice with fixed width L_y and arbitrarily great length L_x with two types of boundary conditions were carried out. In the infinite-length limit, the resultant complex-temperature phase diagram was studied. The results were used to study the approach to the large-q limit of Β, where this locus is the unit circle ζ=1.