# On existence and phase separation of solitary waves for nonlinear Schrödinger systems modelling simultaneous cooperation and competition.

created by soave on 29 Jul 2015

[BibTeX]

Published Paper

Inserted: 29 jul 2015

Journal: Calc. Var. Partial Differential Equations
Volume: 53
Pages: 689--718
Year: 2015
Doi: 10.1007/s00526-014-0764-3
We study existence and phase separation, and the relation between these two aspects, of positive bound states for the nonlinear elliptic system $\begin{cases} - \Delta u_i + \lambda_i u_i = \sum_{j=1}^d \beta_{ij} u_j^2 u_i & \text{in \Omega} \\ u_1 =\cdots = u_d=0 & \text{on \pa \Omega}. \end{cases}$ This system arises when searching for solitary waves for the Gross-Pitaevskii equations. We focus on the case of simultaneous cooperation and competition , that is, we assume that there exist two pairs $(i_1,j_1)$ and $(i_2,j_2)$ such that $\beta_{i_1 j_1}>0$ and $\beta_{i_2 j_2}<0$. Our first main results establishes the existence of solutions with at least $m$ positive components for every $m \leq d$; any such solution is a minimizer of the energy functional $J$ restricted on a Nehari-type manifold $\mathcal{N}$. At a later stage, by means of level estimates on the constrained second differential of $J$ on $\mathcal{N}$, we show that, under some additional assumptions, any minimizer of $J$ on $\mathcal{N}$ has all nontrivial components. In order to prove this second result, we analyse the phase separation phenomena which involve solutions of the system in a not completely competitive framework.