Introducing vdW-DF3 — an accurate van der Waals Density Functional

Recently, we identified the shape of the switching function in the original van der Waals density functional vdW-DF as the key to control the relative contributions of dispersion interactions at different separations (PRB 99, 195418, 2019). Building on this development, we introduce a reformulation that results in significantly higher accuracy for several different classes of systems, in particular for separations beyond the binding distance. This is achieved through tuning the switching function (and thus the non-local correlation) as well as the (semi)local exchange to a set of molecular dimers. Our new formulation provides better binding energies at the equilibrium distance and binding curves of molecular dimers, more accurate interlayer binding energies and lattice constants for layered systems, and improved binding energies for adsorption systems such as small-molecule-adsorption in MOFs and benzene on coinage metals.