Incorrect dissociation behavior of radical ions in density functional calculations

Abstract

The current lineup of popular density functional theories, in particular those based on Becke's exchange functionals, fail to predict a correct dissociation behavior in radical ions where charge and spin must be separated (model:  H₂^•+) or where both must be localized on one fragment (model:  He₂^•+). The repercussions of this on the location of certain transition states on radical ion potential energy surfaces are pointed out.