An improved exchange-correlation potential for polarizability and dissociation in DFT

We propose a novel approach to the problem of polarizabilities and dissociation in electric fields from the static limit of the Vignale-Kohn (VK) functional. We consider the response to the purely scalar part of the VK response potential.This potential has ground-state properties that notably improve over the full VK response density and over usual (semi-)local functionals. The correct qualitative behavior of our potentials means that it is expected to work well for polarizabilities in cases such as the H${}_2$ chain, and it will also correctly dissociate open-shell fragments in a field.