Exchange-correlation functionals from the strong interaction limit of DFT: applications to model chemical systems

We study one-dimensional model chemical systems (representative of their three-dimensional counterparts) using the strictly-correlated electron (SCE) functional, which, by construction, becomes asymptotically exact in the limit of infinite coupling strength. The SCE functional has a highly non-local dependence on the density and is able to capture strong correlation within the Kohn-Sham theory without introducing any symmetry breaking. Chemical systems, however, are not close enough to the strong-interaction limit so that, while ionization energies and the stretched H 2 molecule are accurately described, total energies are in general too low. A correction based on the exact next leading order in the expansion at infinite coupling strength of the Hohenberg-Kohn functional largely improves the results. The strong-interaction limit of DFT provides an exchange-correlation potential that is able to describe strong correlation in 1D model chemical systems.