Functional Extrapolations to Tame Unbound Anions in Density-Functional Theory Calculations
Standard flavors of density-functional theory (DFT) calculations are known to fail in describing anions, due to large self-interaction errors. The problem may be circumvented using localized basis sets of reduced size, leaving no variational flexibility for the extra electron to delocalize. Alternatively, a recent approach exploiting DFT evaluations of total energies on electronic densities optimized at the Hartree-Fock (HF) level has been reported, showing that the self-interaction-free HF densities are able to lead to an improved description of the additional electron, returning affinities in close agreement with the experiments. Nonetheless, such an approach can fail when the HF densitie…
Self-consistent continuum solvation (SCCS): the case of charged systems.
The recently developed self-consistent continuum solvation model (SCCS) [O. Andreussi, I. Dabo, and N. Marzari, J. Chem. Phys. 136, 064102 (2012)] is applied here to charged species in aqueous solutions. Describing ions in solution represents a great challenge because of the large electrostatic interactions between the solute and the solvent. The SCCS model is tested over 106 monocharged species, both cations and anions, and we demonstrate its flexibility, notwithstanding its much reduced set of parameters, to describe charged species in solution. Remarkably low mean absolute errors are obtained with values of 2.27 and 5.54 kcal/mol for cations and anions, respectively. These results are co…