Computationally efficient and accurate dispersion correction for density functional theory

Abstract

The method of dispersion correction as an add-on to standard Kohn-Sham density functional theory (DFT-D) has been refined regarding higher accuracy, broader range of applicability and less empiricism. The main new ingredients are atompair wise specific dispersion coefficients and cut-off radii that are both computed from first principles (TD)DFT for all elements up to Z=94. Geometry dependent information is used for the first time by employing the concept of fractional coordination numbers. They are used to interpolate between dispersion coefficients of atoms in different chemical environments. The method only requires adjustment of two global parameters for each density functional, is asymptotically exact for a gas of weakly interacting neutral atoms and easily allows the computation of atomic forces. It is assessed on standard benchmark sets for inter- and intra-molecular non-covalent interactions with a particular emphasis on a consistent description of light and heavy element systems. The mean absolute deviations for the S22 benchmark set of non-covalent interactions for 11 standard density functionals decreases by 15-40 % compared to the previous (already accurate) DFT-D2 version. Together with virtual-orbital dependent double-hybrid functional, almost CCSD(T) accuracy for a wide range of inter- and intramolecular non-covalent interactions is obtained. Spectacular improvements are also found for peptidefolding models and all tested metallic systems already with standard GGA. We propose the revised method (termed DFT-D3) as a general tool for the fast computation of the dispersion energy in molecules and solids of any kind with DFT and related (low-cost) electronic structure methods for large systems