EN
We revisit Kristály's result on the existence of weak solutions of the Schrödinger equation of the form
-Δu + a(x)u = λb(x)f(u), $x ∈ ℝ^N$, $u ∈ H¹(ℝ^N)$,
where λ is a positive parameter, a and b are positive functions, while $f:ℝ → ℝ$ is sublinear at infinity and superlinear at the origin. In particular, by using Ricceri's recent three critical points theorem, we show that, under the same hypotheses, a much more precise conclusion can be obtained.