A van der Waals density functional built upon the electron-gas foundation

The vdW-DF method is designed to be a systematic extension of the constraint-based generalized-gradient approximation (GGA) and can therefore serve as general purpose density functional [PRB 90, 075148 (2014)]. Yet the early versions can have issues both with bulk systems and with weak chemisorption. We present a recent nonempirical version, vdW-DF-cx [J. Chem. Phys. 140, 18A539 (2014), PRB 89, 035412 (2014)], that resolves these issues. The version is designed to have a consistent combination of exchange and correlation. We show that it performs well for inter-molecular binding and that it can even be better than PBE for describing cohesion and structure of molecules and solids. These results validate the robustness of the vdW-DF plasmon-pole model, which we show is closed linked to the exchange correlation hole of constraint-based GGA.