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Register a new userDecay rates at infinity for solutions to periodic Schr{o}dinger equations
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Authors
Daniel M. Elton
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We consider the equation $Delta u=Vu$ in exterior domains in $mathbb{R}^2$ and $mathbb{R}^3$, where $V$ has certain periodicity properties. In particular we show that such equations cannot have non-trivial superexponentially decaying solutions. As an application this leads to a new proof for the absolute continuity of the spectrum of particular periodic Schr{o}dinger operators. The equation $Delta u=Vu$ is studied as part of a broader class of elliptic evolution equations.
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This paper focuses on the following class of fractional magnetic Schr{o}dinger equations begin{equation*} (-Delta)_{A}^{s}u+V(x)u=g(vert uvert^{2})u+lambdavert uvert^{q-2}u, quad mbox{in } mathbb{R}^{N}, end{equation*} where $(-Delta)_{A}^{s}$ is the fractional magnetic Laplacian, $A :mathbb{R}^N rightarrow mathbb{R}^N$ is the magnetic potential, $sin (0,1)$, $N>2s$, $lambda geq0$ is a parameter, $V:mathbb{R}^N rightarrow mathbb{R}$ is a potential function that may decay to zero at infinity and $g: mathbb{R}_{+} rightarrow mathbb{R}$ is a continuous function with subcritical growth. We deal with supercritical case $qgeq 2^*_s:=2N/(N-2s)$. Our approach is based on variational methods combined with penalization technique and $L^{infty}$-estimates.
We investigate the structure of nodal solutions for coupled nonlinear Schr{o}dinger equations in the repulsive coupling regime. Among other results, for the following coupled system of $N$ equations, we prove the existence of infinitely many nodal solutions which share the same componentwise-prescribed nodal numbers begin{equation}label{ab} left{ begin{array}{lr} -{Delta}u_{j}+lambda u_{j}=mu u^{3}_{j}+sum_{i eq j}beta u_{j}u_{i}^{2} ,,,,,,, in W , u_{j}in H_{0,r}^{1}(W), ,,,,,,,,j=1,dots,N, end{array} right. end{equation} where $W$ is a radial domain in $mathbb R^n$ for $nleq 3$, $lambda>0$, $mu>0$, and $beta <0$. More precisely, let $p$ be a prime factor of $N$ and write $N=pB$. Suppose $betaleq-frac{mu}{p-1}$. Then for any given non-negative integers $P_{1},P_{2},dots,P_{B}$, (ref{ab}) has infinitely many solutions $(u_{1},dots,u_{N})$ such that each of these solutions satisfies the same property: for $b=1,...,B$, $u_{pb-p+i}$ changes sign precisely $P_b$ times for $i=1,...,p$. The result reveals the complex nature of the solution structure in the repulsive coupling regime due to componentwise segregation of solutions. Our method is to combine a heat flow approach as deformation with a minimax construction of the symmetric mountain pass theorem using a $mathbb Z_p$ group action index. Our method is robust, also allowing to give the existence of one solution without assuming any symmetry of the coupling.
In this paper, we study the nonlinear Schr{o}dinger equation $ -Delta u+V(x)u=f(x,u) $on the lattice graph $ mathbb{Z}^{N}$. Using the Nehari method, we prove that when $f$ satisfies some growth conditions and the potential function $V$ is periodic or bounded, the above equation admits a ground state solution. Moreover, we extend our results from $mathbb{Z}^{N}$ to quasi-transitive graphs.
In this paper, we study important Schr{o}dinger systems with linear and nonlinear couplings begin{equation}label{eq:diricichlet} begin{cases} -Delta u_1-lambda_1 u_1=mu_1 |u_1|^{p_1-2}u_1+r_1beta |u_1|^{r_1-2}u_1|u_2|^{r_2}+kappa (x)u_2~hbox{in}~mathbb{R}^N, -Delta u_2-lambda_2 u_2=mu_2 |u_2|^{p_2-2}u_2+r_2beta |u_1|^{r_1}|u_2|^{r_2-2}u_2+kappa (x)u_1~ hbox{in}~mathbb{R}^N, u_1in H^1(mathbb{R}^N), u_2in H^1(mathbb{R}^N), onumber end{cases} end{equation} with the condition $$int_{mathbb{R}^N} u_1^2=a_1^2, int_{mathbb{R}^N} u_2^2=a_2^2,$$ where $Ngeq 2$, $mu_1,mu_2,a_1,a_2>0$, $betainmathbb{R}$, $2<p_1,p_2<2^*$, $2<r_1+r_2<2^*$, $kappa(x)in L^{infty}(mathbb{R}^N)$ with fixed sign and $lambda_1,lambda_2$ are Lagrangian multipliers. We use Ekland variational principle to prove this system has a normalized radially symmetric solution for $L^2-$subcritical case when $Ngeq 2$, and use minimax method to prove this system has a normalized radially symmetric positive solution for $L^2-$supercritical case when $N=3$, $p_1=p_2=4, r_1=r_2=2$.
In this paper, we study the existence and instability of standing waves with a prescribed $L^2$-norm for the fractional Schr{o}dinger equation begin{equation} ipartial_{t}psi=(-Delta)^{s}psi-f(psi), qquad (0.1)end{equation} where $0<s<1$, $f(psi)=|psi|^{p}psi$ with $frac{4s}{N}<p<frac{4s}{N-2s}$ or $f(psi)=(|x|^{-gamma}ast|psi|^2)psi$ with $2s<gamma<min{N,4s}$. To this end, we look for normalized solutions of the associated stationary equation begin{equation} (-Delta)^s u+omega u-f(u)=0. qquad (0.2) end{equation} Firstly, by constructing a suitable submanifold of a $L^2$-sphere, we prove the existence of a normalized solution for (0.2) with least energy in the $L^2$-sphere, which corresponds to a normalized ground state standing wave of(0.1). Then, we show that each normalized ground state of (0.2) coincides a ground state of (0.2) in the usual sense. Finally, we obtain the sharp threshold of global existence and blow-up for (0.1). Moreover, we can use this sharp threshold to show that all normalized ground state standing waves are strongly unstable by blow-up.
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