A fitted van der Waals density functional with accurate short and long-range interactions

A fitting scheme has been developed to create a new van der Waals density functional, called vdW-DF-fit. The original vdW-DF kernel, as well as the plasmon dispersion model, are numerically modified and fitted to minimize the binding energy and separation errors with respect to experimental/RPA/high-level quantum chemistry results of a list of commonly used reference datasets (S22, A24, X40, S66 etc.). We are also pursuing automated fitting schemes using machine-learning techniques. This is work in progress and we are reporting first, promising results.