The compactness of minimizing sequences for a nonlinear Schr\"odinger system with potentials

TL;DR

This paper investigates the conditions under which minimizing sequences for a constrained energy functional in a nonlinear Schrödinger system with potentials are compact, considering different boundedness scenarios of the potentials.

Contribution

It provides new insights into the compactness properties of minimizing sequences for a class of nonlinear Schrödinger systems with potentials, under specific assumptions.

Findings

Established compactness criteria for minimizing sequences.

Analyzed the impact of potential boundedness on sequence behavior.

Extended previous results to systems with multiple constraints.

Abstract

In this paper, we consider the following minimizing problem with two constraints: \[ \inf \left\{ E(u) | u=(u_1,u_2), \ \| u_1 \|_{L^2}^2 = \alpha_1, \ \| u_2 \|_{L^2}^2 = \alpha_2 \right\}, \] where $\alpha_1,\alpha_2 > 0$ and $E(u)$ is defined by \[ E(u) := \int_{\mathbf{R}^N} \left\{\frac{1}{2} \sum_{i=1}^2 \left( |\nabla u_1|^2 + V_i (x) |u_i|^2 \right) - \sum_{i=1}^2 \frac{\mu_i}{2p_i+2} |u_i|^{2p_i+2} - \frac{\beta}{p_3+1} |u_1|^{p_3+1} |u_2|^{p_3+1} \right\} \mathrm{d} x. \] Here $N \geq 1$, $ \mu_1,\mu_2,\beta > 0$ and $V_i(x)$ $(i=1,2)$ are given functions. For $V_i(x)$, we consider two cases: (i) both of $V_1$ and $V_2$ are bounded, (ii) one of $V_1$ and $V_2$ is bounded. Under some assumptions on $V_i$ and $p_j$, we discuss the compactness of any minimizing sequence.