PSEUDOTEMPERATURE MONTE-CARLO STUDY OF A GROUND-STATE PHASE-TRANSITION OF THE ANTIFERROMAGNETIC SPIN-S ISING-MODEL ON A TRIANGULAR LATTICE

We have studied a ground-state phase transition in an S space of a spin-S antiferromagnetic Ising model on a triangular lattice, by using Monte Carlo simulations with a pseudotemperature. The critical index eta decreases from the value 1/2 for the S = 1/2 system as S increases and becomes zero for S > S-c. We introduce an occupation number of hard hexagons to the system with the pseudotemperature. From the behavior of the sublattice magnetization and the occupation number of hard hexagon, the critical value of spin S-c is estimated to be 3.