Sign-changing solutions of competition–diffusion elliptic systems and optimal partition problems

In this paper we prove the existence of infinitely many sign-changing solutions for the system of $m$ Schr\"odinger equations with competition interactions $$-\Delta u_i+a_i u_i^3+\beta u_i \sum_{j\neq i} u_j^2 =\lambda_{i,\beta} u_i \quad u_i\in H^1_0(\Omega), \quad i=1,...,m$$ where $\Omega$ is a bounded domain, $\beta>0$ and $a_i\geq 0\ \forall i.$ Moreover, for $a_i=0$, we show a relation between critical energies associated with this system and the optimal partition problem $$\mathop{\inf_{\omega_i\subset \Omega \text{open}}}_{\omega_i\cap \omega_j=\emptyset\forall i\neq j} \sum_{i=1}^{m} \lambda_{k_i}(\omega_i),$$ where $\lambda_{k_i}(\omega)$ denotes the $k_i$--th eigenvalue of $-\Delta$ in $H^1_0(\omega)$. In the case $k_i\leq 2$ we show that the optimal partition problem appears as a limiting critical value, as the competition parameter $\beta$ diverges to $+\infty$.Comment: 25 page

Two Positive Normalized Solutions and Phase Separation for Coupled Schr\"odinger Equations on Bounded Domain with L2-Supercritical and Sobolev Critical or Subcritical Exponent

In this paper we study the existence of positive normalized solutions of the following coupled Schr\"{o}dinger system: \begin{align} \left\{ \begin{aligned} & -\Delta u = \lambda_u u + \mu_1 u^3 + \beta uv^2, \quad x \in \Omega, \\ & -\Delta v = \lambda_v v + \mu_2 v^3 + \beta u^2 v, \quad x \in \Omega, \\ & u > 0, v > 0 \quad \text{in } \Omega, \quad u = v = 0 \quad \text{on } \partial\Omega, \end{aligned} \right. \nonumber \end{align} with the $L^2$ constraint \begin{align} \int_{\Omega}|u|^2dx = c_1, \quad \quad \int_{\Omega}|v|^2dx = c_2, \nonumber \end{align} where $\mu_1, \mu_2 > 0$, $\beta \neq 0$, $c_1, c_2 > 0$, and $\Omega \subset \mathbb{R}^N$ ($N = 3, 4$) is smooth, bounded, and star-shaped. Note that the nonlinearities and the coupling terms are both $L^2$-supercritical in dimensions 3 and 4, Sobolev subcritical in dimension 3, Sobolev critical in dimension 4. We show that this system has a positive normalized solution which is a local minimizer. We further show that the system has a second positive normalized solution, which is of M-P type when $N = 3$. This seems to be the first existence result of two positive normalized solutions for such a Schr\"{o}dinger system, especially in the Sobolev critical case. We also study the limit behavior of the positive normalized solutions in the repulsive case $\beta \to -\infty$, and phase separation is expected.Comment: 32 page

International Conference on Nonlinear Differential Equations and Applications

Dear Participants, Colleagues and Friends It is a great honour and a privilege to give you all a warmest welcome to the first Portugal-Italy Conference on Nonlinear Differential Equations and Applications (PICNDEA). This conference takes place at the Colégio Espírito Santo, University of Évora, located in the beautiful city of Évora, Portugal. The host institution, as well the associated scientific research centres, are committed to the event, hoping that it will be a benchmark for scientific collaboration between the two countries in the area of mathematics. The main scientific topics of the conference are Ordinary and Partial Differential Equations, with particular regard to non-linear problems originating in applications, and its treatment with the methods of Numerical Analysis. The fundamental main purpose is to bring together Italian and Portuguese researchers in the above fields, to create new, and amplify previous collaboration, and to follow and discuss new topics in the area

Construction of a solution for the two-component radial Gross-Pitaevskii system with a large coupling parameter

We consider strongly coupled competitive elliptic systems that arise in the study of two-component Bose-Einstein condensates. As the coupling parameter tends to infinity, solutions that remain uniformly bounded are known to converge to a segregated limiting profile, with the difference of its components satisfying a limit scalar PDE. In the case of radial symmetry, under natural non-degeneracy assumptions on a solution of the limit problem, we establish by a perturbation argument its persistence as a solution to the elliptic system