ANTIFERROMAGNETIC TRIANGULAR ISING-MODEL - CRITICAL-BEHAVIOR OF THE GROUND-STATE

The critical ground state of the antiferromagnetic triangular Ising mo del is studied with finite-size scaling, with the use of exact techniq ues and numerical transfer-matrix methods. Exact solution of the model in zero field yields a conformal anomaly equal to 1, and values of cr itical exponents. For nonzero fields, dominant eigenvalues of the tran sfer matrix are computed for systems with linear dimensions up to 27 w ith the use of an efficient coding of spin states as a system of nonin tersecting strings. The results are in perfect agreement with the Gaus sian-model-Coulomb-gas scenario proposed by Nienhuis et al. for this m odel. Quantitative agreement is found with the predictions for exponen ts of spin-wave and vortex operators. Furthermore, we locate the field -induced Kosterlitz-Thouless transition to a long-range-ordered state at a field H(c) = 0. 266 +/- 0.010.