Infinitely many homoclinic solutions for a class of subquadratic second-order Hamiltonian systems

In this paper, we mainly consider the existence of infinitely many homoclinic solutions for a class of subquadratic second-order Hamiltonian systems u¨−L(t)u+Wu(t,u)=0, where L(t) is not necessarily positive definite and the growth rate of potential function W can be in (1, 3/2). Using the variant fountain theorem, we obtain the existence of infinitely many homoclinic solutions for the second-order Hamiltonian systems.