Multiplicity of solutions for a class of semilinear Schrِdinger equations with sign-changing potential

In this paper, we study the existence of infinitely many nontrivial solutions for a class of semilinear Schrödinger equations − Δ u + V ( x ) u = f ( x , u ) , x ∈ R N , where the primitive of the nonlinearity f is of superquadratic growth near infinity in u and the potential V is allowed to be sign-changing.