Semiclassical Limit For the Nonlinear Klein Gordon Equation in Bounded Domains

We are interested in the existence of standing waves for the nonlinear Klein Gordon equation εWe want to use a Benci-Cerami type argument in order to prove a the existence of several standing waves localized in suitable points of D. The main result of this paper is that, under suitable growth condition on W, for ε suffciently small, we have at least cat(D) stationary solutions of equation (†), where cat(D) is the Ljusternik-Schnirelmann category. The proof is achieved by solving a constrained critical point problem via variational techniques.