Gap inhomogeneities and the density of states in disordered d-wave superconductors

We report on a numerical study of disorder effects in 2D d-wave BCS superconductors. We compare exact numerical solutions of the Bogoliubov-de Gennes (BdC) equations for the density of states rho (E) with the standard T-matrix approximation. Local suppression of the order parameter near impurity sites, which occurs in self-consistent solutions of the BdC equations, leads to apparent power-law behavior rho>(*) over bar * (E) similar to \E\(alpha) with nonuniversal alpha over an energy scale comparable to the single-impurity resonance energy Omega (0) We show that the novel effects arise from static spatial correlations between the order parameter and the impurity distribution.