INTERACTING DOMAIN-WALLS AND THE 5-VERTEX MODEL

We investigate the thermodynamic and critical properties of an interac ting-domain-wall model which is derived from the triangular-lattice an tiferromagnetic Ising model with the anisotropic nearest- and next-nea rest-neighbor interactions. The model is equivalent to the general fiv e-vertex model. Diagonalizing the transfer matrix exactly by the Bethe Ansatz method, we obtain the phase diagram displaying the commensurat e and incommensurate (IC) phases separated by the Pokrovsky-Talapov tr ansitions. The phase diagram exhibits commensurate phases where the do main-wall density q is locked at the values of 0, 1/2, and 1. The IC p hase is a critical state described by the Gaussian fixed point. The ef fective Gaussian coupling constant is obtained analytically and numeri cally for the IC phase using the finite-size-scaling predictions of th e conformal-field theory. It takes the value 1/2 in the noninteracting limit and also at the boundaries of q = 0 or 1 phase and the value 2 at the boundary of q = 1/2 phase, while it varies smoothly throughout the IC region.