THE NONINTERACTING HARD-SQUARE LATTICE-GAS - ISING UNIVERSALITY

The critical exponents of the non-interacting hard-square lattice gas model are determined by means of series analysis and finite-size scali ng. The series analysis leads to results for the exponents that arc co nsistent with the expected Ising universal values. A scaling analysis is performed on different types of numerical finite-size data obtained by means of the transfer-matrix method. The results support Ising uni versality- A procedure based on conformal invariance reproduces the kn own Ising temperature and magnetic exponents within 10(-6). Furthermor e we estimate the critical density of the hard-square model as rho(c) = 0.367 743 000 (5).