title: Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001).
abstract: In this work, a range of van der Waals type density functionals are applied to the H2O/NaCl(001) and H2O/MgO(001) interface systems to explore the effect of an explicit dispersion treatment. The functionals we use are the self-consistent vdW functionals vdW-DF, vdW-DF2, optPBE-vdW, optB88-vdW, optB86b-vdW, and vdW-DF-cx, as well as the dispersion-corrected PBE-TS and PBE-D2 methods; they are all compared with the standard PBE functional. For both NaCl(001) and MgO(001), we find that the dispersion-flavoured functionals stabilize the water-surface interface by approximately 20%-40% compared to the PBE results. For NaCl(001), where the water molecules remain intact for all overlayers, the dominant contribution to the adsorption energy from "density functional theory dispersion" stems from the water-surface interactions rather than the water-water interactions. The optPBE-vdW and vdW-DF-cx functionals yield adsorption energies in good agreement with available experimental values for both NaCl and MgO. To probe the strengths of the perturbations of the adsorbed water molecules, we also calculated water dipole moments and found an increase up to 85% for water at the MgO(001) surface and 70% at the NaCl(001) surface, compared to the gas-phase dipole moment.
authors.affiliation: Department of Chemistry-Ångström, Uppsala University, Box 538, SE-751 21Uppsala, Sweden.
authors.forename: Getachew G
authors.initials: GG
authors.lastname: Kebede
authors.affiliation: Department of Chemistry-Ångström, Uppsala University, Box 538, SE-751 21Uppsala, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Spångberg
authors.affiliation: Department of Chemistry-Ångström, Uppsala University, Box 538, SE-751 21Uppsala, Sweden.
authors.forename: Pavlin D
authors.initials: PD
authors.lastname: Mitev
authors.affiliation: Department of Chemistry-Ångström, Uppsala University, Box 538, SE-751 21Uppsala, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Broqvist
authors.affiliation: Department of Chemistry-Ångström, Uppsala University, Box 538, SE-751 21Uppsala, Sweden.
authors.forename: Kersti
authors.identifier: 0000000323520458
authors.initials: K
authors.lastname: Hermansson