Ground state solutions for the nonlinear Schrödinger–Maxwell equations

In this paper we study the nonlinear Schrödinger–Maxwell equations{−Δu+V(x)u+ϕu=|u|p−1uin R3,−Δϕ=u2in R3. If V   is a positive constant, we prove the existence of a ground state solution (u,ϕ)(u,ϕ) for 2