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

Abstract

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 H₂ 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.