Multiplicity of solutions for fractional Hamiltonian systems with Liouville-Weyl fractional derivative

摘要

In this paper, we investigate the existence of infinitely many solutions forthe following fractional Hamiltonian systems: \begin{eqnarray}\label{eq00}_{t}D_{\infty}^{\alpha}(_{-\infty}D_{t}^{\alpha}u(t)) + L(t)u(t) = & \nablaW(t,u(t))\\ u\in H^{\alpha}(\mathbb{R}, \mathbb{R}^{N}).\nonumber\end{eqnarray} where $\alpha \in (1/2, 1)$, $t\in \mathbb{R}$, $u\in\mathbb{R}^{n}$, $L\in C(\mathbb{R}, \mathbb{R}^{n^2})$ is a symmetric andpositive definite matrix for all $t\in \mathbb{R}$, $W\inC^{1}(\mathbb{R}\times \mathbb{R}^{n}, \mathbb{R})$, and $\nabla W$ is thegradient of $W$ at $u$. The novelty of this paper is that, assuming thereexists $l\in C(\mathbb{R}, \mathbb{R})$ such that $(L(t)u,u)\geq l(t)|u|^{2}$for all $t\in \mathbb{R}$, $u\in \mathbb{R}^{n}$ and the following conditionson $l$: $\inf_{t\in \mathbb{R}}l(t) >0$ and there exists $r_{0}>0$ such that,for any $M>0$ $$ m(\{t\in (y-r_{0}, y+r_{0})/\;\;l(t)\leq M\}) \to 0\;\;\mbox{as}\;\;|y|\to\infty. $$ are satisfied and $W$ is of subquadratic growth as $|u| \to +\infty$, we showthat (\ref{eq00}) possesses infinitely many solutions via the genus propertiesin the critical theory. Recent results in [Z. Zhang and R. Yuan, Solutions forsubquadratic fractional Hamiltonian systems without coercive conditions, Math.Methods Appl. Sci., DOI: 10.1002/mma.3031] are significantly improved.