Self-dual transfer matrix renormalization for the triangular Potts model

The transfer matrix renormalization method is utilized to obtain an approximate renormalization group transformation for the Potts model on triangular lattice with two- and three-site interactions in every other triangular face. The transformation preserves exact duality of the model and hence produces exact critical surfaces. Fixed point and scaling exponents are found to be identical to that of the hamiltonian version of the model.