Convergence of the density of states and delocalization of eigenvectors on random regular graphs

Abstract

Consider a random regular graph of fixed degree $d$ with $n$ vertices. We study spectral properties of the adjacency matrix and of random Schrödinger operators on such a graph as $n$ tends to infinity.

We prove that the integrated density of states on the graph converges to the integrated density of states on the infinite regular tree and we give uniform bounds on the rate of convergence. This allows to estimate the number of eigenvalues in intervals of size comparable to ${\log }_{d-1}^{-1}(n)$. Based on related estimates for the Green function we derive results about delocalization of eigenvectors.