Physical review. B, Condensed matter
Sparse-matrix analysis of spin-(1/2) Ising systems
Norman H. Fuchs, S. Gartenhaus
Abstract
We describe an extension of an approximation scheme proposed earlier for calculating the critical properties of spin-(1/2) Ising systems in terms of the duo-diagonal, sparse matrices of Kramers and Wannier. The computational framework is refined and extended to accommodate a variety of two-, three-, and higher-dimensional lattices as well as interactions other than nearest neighbor. The relation between the underlying symmetries of the lattice and the structure of its associated phase diagram is clarified. Making use of a probabilistic interpretation for the components of the eigenvectors associated with the maximum eigenvalue of the duo-diagonal matrices, it is shown that this makes practical the computation of various thermodynamic quantities---as well as correlation functions---in terms of the expectation values of appropriate operators taken between these eigenvectors. When combined with the techniques of finite-size scaling the present scheme is confirmed to be effective for extracting the critical-point properties of the infinite lattice.