Domain-wall renormalization-group study of the two-dimensional random Ising model

The distribution of domain-wall free energies is calculated with the use of a transfer-matrix approach for finite lattices. A renormalization-group transformation is set up which preserves the domain-wall free-energy distribution as well as the susceptibility when the lattice parameter is changed. The fixed points, critical exponents, and phase diagram are determined for the two-dimensional random Ising model with a Gaussian distribution of nearest-neighbor interactions.