SINGULARLY PERTURBED NONLINEAR DIRICHLET PROBLEMS WITH A GENERAL NONLINEARITY

Let Omega be a bounded domain in R(n), n >= 3, with a boundary partial derivative Omega is an element of C(2). We consider the following singularly perturbed nonlinear elliptic problem oil Omega: epsilon(2)Delta u - u + f(u) = 0, u > 0 on Omega, n = 0 on partial derivative Omega, where the nonlinearity f is of subcritical growth. Under rather strong conditions on f, it has been known that for small epsilon > 0, there exists a mountain pass solution u(epsilon) of above problem which exhibits a spike layer near a maximum point of the distance function d from partial derivative Omega as epsilon -> 0. In this paper, we construct a solution u(epsilon) of above problem which exhibits a spike layer near a maximum point of the distance function under certain conditions on f, which we believe to be almost optimal.