Concentration of nodal solutions for semiclassical quadratic choquard equations

In this article concerns the semiclassical Choquard equation -epsilon 2 Delta u+ V(x)u = epsilon-2( 1 |center dot| * u2)u for x is an element of R3 and small epsilon. We establish the existence of a sequence of localized nodal solutions concentrating near a given local mini-mum point of the potential function V, by means of the perturbation method and the method of invariant sets of descending flow.