Least energy sign-changing solutions for Schrodinger-Poisson systems with potential well

In this article, we investigate the existence of least energy sign-changing solutions for the following Schrodinger-Poisson system {-Delta u + V(x)u + K(x)phi u = f(u), x is an element of R-3, -Delta phi = K(x)u(2), x is an element of R-3, where the functions V(x), K(x) have finite limits as vertical bar x vertical bar -> infinity satisfying some mild assumptions. By combining variational methods with the global compactness lemma, we obtain a least energy sign-changing solution with exactly two nodal domains, and its energy is strictly larger than twice that of least energy solutions.