Infinitely Many Solutions for Sublinear Modified Nonlinear Schrödinger Equations Perturbed from Symmetry

Abstract

In this paper, we consider the existence of infinitely many solutions for the following perturbed modified nonlinear Schrödinger equations \[ \begin{cases} -\Delta u - \Delta(|u|^{\alpha}) |u|^{\alpha-2}u = g(x,u) + h(x,u) &x \in \Omega, \\ u = 0 &x \in \partial \Omega, \end{cases} \] where $\Omega$ is a bounded smooth domain in $\mathbb{R}^N$ ($N \geq 1$) and $\alpha \geq 2$. Under the condition that $g(x,u)$ is sublinear near origin with respect to $u$, we study the effect of non-odd perturbation term $h(x,u)$ which breaks the symmetry of the associated energy functional. With the help of modified Rabinowitz's perturbation method and the truncation method, we prove that this equation possesses a sequence of small negative energy solutions approaching to zero.