Published online by Cambridge University Press: 26 June 2023
We consider the non-linear Schrödinger equation(Pμ)\begin{equation*}\begin{array}{lc}-\Delta u + V(x) u = \mu f(u) + |u|^{2^*-2}u, &\end{array}\end{equation*}
$\mathbb{R}^N$,
$N\geq3$, where V changes sign and
$f(s)/s$, s ≠ 0, is bounded, with V non-periodic in x. The existence of a solution is established employing spectral theory, a general linking theorem due to [12] and interaction between translated solutions of the problem at infinity with some qualitative properties of them.