On the number of sign-changing solutions of a semiclassical nonlinear Schrödinger equation

Abstract

We study the following nonlinear Schrödinger equation: $$ {\varepsilon}^2\Delta u-V(x) u+|u|^{p-1}u=0 \ \hbox{in}\ \mathbb R^N,$$ where ${\varepsilon}>0$, $u,V:\mathbb R^N\to\mathbb R$, $p>1$. We prove that, under suitable conditions on the symmetry of $V$, the set of sign-changing solutions has a rich structure in the semiclassical limit ${\varepsilon}\to 0$: we construct multipeak solutions with an arbitrarily large number of positive and negative peaks which collapse to either a local minimum or a local maximum of $V.$ The proof relies on a local approach and is based on the finite-dimensional reduction, in the spirit of the arguments employed in [15].