Universality in the partially anisotropic three-dimensional Ising lattice

Using transfer-matrix extended phenomenological renormalization-group methods, we study the critical properties of the spin-1/2 Ising model on a simple-cubic lattice with partly anisotropic coupling strengths (J) over right arrow = (J', J', J). The universality of both fundamental critical exponents y(t) and y(h) is confirmed. It is shown that the critical finite-size scaling amplitude ratios U = A(chi)((4))A(kappa)/A(chi)(2), Y-1 = A(kappa)(')/A(chi), and Y-2 = A(kappa)((4))/A(chi)((4)) are independent of the lattice anisotropy parameter Delta = J(')/J. For the Y-2 invariant of the three-dimensional Ising universality class, we give the first quantitative estimate Y-2 approximate to 2.013 (shape L x L x infinity, periodic boundary conditions in both transverse directions). (C) 2004 MAIK "Nauka / Interperiodica".