Normalized solutions of nonlinear Schrödinger equations

Abstract

We consider the problem -Δu - g(u) = λu, u \in H^1(\R^N), \int_{\R^N} u^2 = 1, λ\in\R, in dimension $N\ge 2$. Here $g$ is a superlinear, subcritical, possibly nonhomogeneous, odd nonlinearity. We deal with the case where the associated functional is not bounded below on the $L^2$-unit sphere, and we show the existence of infinitely many solutions.