title: Elimination of Spurious Fractional Charges in Dissociating Molecules by Correcting the Shape of Approximate Kohn-Sham Potentials.
abstract: Standard density-functional approximations often incorrectly predict that heteronuclear diatomic molecules dissociate into fractionally charged atoms. We demonstrate that these spurious charges can be eliminated by adapting the shape-correction method for Kohn-Sham potentials that was originally introduced to improve Rydberg excitation energies [ Phys. Rev. Lett. 2012 , 108 , 253005 ]. Specifically, we show that if a suitably determined fraction of electron charge is added to or removed from a frontier Kohn-Sham orbital level, the approximate Kohn-Sham potential of a stretched molecule self-corrects by developing a semblance of step structure; if this potential is used to obtain the electron density of the neutral molecule, charge delocalization is blocked and spurious fractional charges disappear beyond a certain internuclear distance.
authors.affiliation: Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada.
authors.forename: Darya N
authors.initials: DN
authors.lastname: Komsa
authors.affiliation: Department of Chemistry, The University of Western Ontario , London, Ontario N6A 5B7, Canada.
authors.forename: Viktor N
authors.initials: VN
authors.lastname: Staroverov