Improved DFT Adsorption Energies with Semiempirical Dispersion Corrections

Over the past years, density functional theory (DFT) became a widely approved and successful method for calculating properties of various materials and molecules. Especially suited for systems with delocalized electrons like metals, the efficient treatment of the van der Waals interaction remained a problem for DFT functionals within the generalized gradient approximation (GGA). Combining Grimme's D3 correction with the RPBE functional and using a previously published data set, we show that this yields a functional that is well-suited for an accurate and balanced description of adsorption energies. The RPBE-D3 approach performs comparably to higher-level methods such as the BEEF-vdW and the SW-R88 method. Even for oxide systems, which traditionally are not well-described by GGA functionals, RPBE-D3 leads to satisfactorily results when combined with the +U approach, as demonstrated with respect to the energetic ordering of the three TiO₂ polymorphs rutile, anatase, and brookite.