Existence and nonexistence of normalized solutions for nonlinear Schrödinger equation involving combined nonlinearities in bounded domain
In this paper, we consider the existence, multiplicity and nonexistence of solutions for the following equation \begin{equation*} \begin{cases} \begin{aligned} &-Δu+ωu=μu^{p-1}+u^{q-1},~ u>0 \quad &&\text { in } Ω, \\ &u=0 &&\text { on } \partialΩ, \\ \end{aligned} \end{cases} \end{equation*} with prescribed $L^2$-norm $\|u\|_2^2=ρ$, where $N\ge 1$, $ρ>0$, $μ\in \mathbb{R}$, $1<p\le q$, and $Ω\subset\mathbb{R}^N$ is a bounded smooth domain. The parameter $ω\in\mathbb{R}$ arises as a Lagrange multiplier. Firstly, when $2<p\le q\le \frac{2N}{(N-2)^+}$ and $ρ$ is small, we establish the existence of a local minimizer of energy. Furthermore, when $μ\ge 0$ and $Ω$ is a star-shaped domain, using the monotonicity trick and the Pohozaev identity, we show that there exists a second solution which is of mountain pass type. Secondly, when $μ\ge 0$, $N\ge 3$, $1<p\le 2$, $q\ge \max\left\{\frac{2N}{N-2}, 3\right\}$ and $Ω$ is a convex domain, using the moving-plane method, we prove the nonexistence of normalized solutions for large $ρ$. Finally, when $μ=0$, $N\ge 3$, $q=\frac{2N}{N-2}$ and $Ω$ is a ball, we give a dichotomy result of normalized solutions for the Brézis-Nirenberg problem by continuation arguments.