Asymptotic eigenfunctions for a class of difference operators

Abstract

We analyze a general class of difference operators He = Te + Ve on � 2 ((eZ) d ), where Ve is a one-well potential and e is a small parameter. We construct formal asymptotic expansions of WKB-type for eigenfunctions associated with the low lying eigenvalues of He. These are obtained from eigenfunctions or quasimodes for the operator He, acting on L 2 (R d ), via restriction to the lattice (eZ) d .