Multiple solutions for a class of Schrödinger–Poisson system with indefinite nonlinearity

In this article, we investigate the existence and multiplicity of solutions of Schrödinger–Poisson system{−Δu+u+l(x)ϕu=k(x)|u|2u+λh(x)u,x∈R3−Δϕ=l(x)u2,x∈R3 where the potential k(x)k(x) allows sign changing. We obtain the existence and multiplicity of solutions for the system, which can be regarded as complementary work of Huang et al. (2013) [12].