Improved DFT adsorption energies with semi-empirical dispersion corrections

Over the past years, density functional theory (DFT) became a widely approved and successfull method for calculating properties of various materials and molecules. Especially suited for systems with delocalized electrons like metals, the efficient treatment of 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 dataset, 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 comparable 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.