HYPERUNIVERSAL AMPLITUDE RATIOS AND THE CENTRAL CHARGE OF THE SPIN-ONE ISING-MODEL

The second moment of the spin-spin correlation function mu(2) = Sigma( ij)gamma(ij)(2)([SiSj]-[S-i][S-j]) for the spin-one, square lattice, I sing model is expanded in powers of h = exp[-(H/kT)] for arbitrary val ues of upsilon = exp(-J/kT). The expansion coefficients are calculated complete to order h(perpendicular to 2). By hyperscaling, this quanti ty has a quadratic divergence as the critical point (T = T-c, H = 0) i s approached along the field axis (T = T-c, H --> 0). The amplitude fo r this divergence is estimated by series analysis methods. The resulti ng central charge for the model is consistent with the known value of 1/2.