Revista Matemática Iberoamericana


Full-Text PDF (352 KB) | Metadata | Table of Contents | RMI summary
Volume 21, Issue 3, 2005, pp. 771–818
DOI: 10.4171/RMI/435

Published online: 2005-12-31

Potential Theory for Schrödinger operators on finite networks

Enrique Bendito[1], Ángeles Carmona[2] and Andrés M. Encinas[3]

(1) Universitat Politècnica de Catalunya, Barcelona, Spain
(2) Universitat Politècnica de Catalunya, Barcelona, Spain
(3) Universitat Politècnica de Catalunya, Barcelona, Spain

We aim here at analyzing the fundamental properties of positive semidefinite Schrödinger operators on networks. We show that such operators correspond to perturbations of the combinatorial Laplacian through 0-order terms that can be totally negative on a proper subset of the network. In addition, we prove that these discrete operators have analogous properties to the ones of elliptic second order operators on Riemannian manifolds, namely the monotonicity, the minimum principle, the variational treatment of Dirichlet problems and the condenser principle. Unlike the continuous case, a discrete Schrödinger operator can be interpreted as an integral operator and therefore a discrete Potential Theory with respect to its associated kernel can be built. We prove that the Schrödinger kernel satisfies enough principles to assure the existence of equilibrium measures for any proper subset. These measures are used to obtain systematic expressions of the Green and Poisson kernels associated with Dirichlet problems.

Keywords: Combinatorial Laplacian, Schrödinger operators, Dirichlet forms, Green kernel, Poisson kernel, Discrete Potential Theory, equilibrium measures, effective resistance

Bendito Enrique, Carmona Ángeles, Encinas Andrés: Potential Theory for Schrödinger operators on finite networks. Rev. Mat. Iberoam. 21 (2005), 771-818. doi: 10.4171/RMI/435