# The role of potential, Morawetz estimate and spacetime bound for quasilinear Schr\"{o}dinger equations

## TL;DR

This paper investigates the global existence and blowup criteria for quasilinear Schrödinger equations with potential, establishing Morawetz estimates and spacetime bounds under specific conditions on the potential and initial data.

## Contribution

It classifies potential functions into categories affecting solution behavior and derives Morawetz estimates and spacetime bounds for global solutions.

## Key findings

- Potential classification determines solution blowup or global existence.
- Morawetz estimates provide decay and integrability properties.
- Spacetime bounds quantify solution regularity over time.

## Abstract

In this paper, we deal with the following Cauchy problem \begin{equation*} \left\{ \begin{array}{lll} iu_t = \Delta u + 2uh'(|u|^2)\Delta h(|u|^2) + V(x)u,\ x\in \mathbb{R}^N,\ t>0\\ u(x,0) = u_0(x), \quad x \in \mathbb{R}^N. \end{array}\right. \end{equation*} Here $h(s)$ and $V(x)$ are some real functions. We take the potential $V(x)\in L^q(\mathbb{R}^N)+L^{\infty}(\mathbb{R}^N)$ as criterion of the blowup and global existence of the solution to (1.1). In some cases, we can classify it in the following sense: If $V(x)\in S(I)$, then the solution of (1.1) is always global existence for any $u_0$ satisfying $0<E(u_0)<+\infty$; If $V(x)\in S(II)$, then the solution of (1.1) may blow up for some initial data $u_0$. Here $$ S(I)=\cup_{q>q_c}[L^q(\mathbb{R}^N)+L^{\infty}(\mathbb{R}^N)],\quad S(II)=\left\{\cup_{q<q_c}[L^q(\mathbb{R}^N)+L^{\infty}(\mathbb{R}^N)]\right\}\setminus S(I).$$ Under certain assumptions, we also establish Morawetz estimates and spacetime bounds for the global solution, for example, \begin{align*} &\int_0^{+\infty} \int_{\mathbb{R}^N }\frac{[|\nabla h(|u|^2)|^2 + |V(x)||u|^2]}{(|x|+t)^{\lambda}}dxdt\leq C,\\ & \|u\|_{L^{\bar{q}}_t (\mathbb{R}) L^{\bar{r}}_x(\mathbb{R}^N)} = \left(\int_0^{+\infty} \left(\int_{\mathbb{R}^N}|u|^{\bar{r}} dx\right)^{\frac{\bar{q}}{\bar{r}}} dt\right)^{\frac{1}{\bar{q}}} \leq C. \end{align*}