A universal damping function for empirical dispersion correction on density functional theory

A damped London dispersion interaction is generally adopted in empirical dispersion corrections on density functional theory (DFT), where dispersion parameters are determined empirically to reproduce correct dispersive interactions after assuming a damping function. The key to a successful dispersion correction is choosing an appropriate damping function. In this work we propose a single universal damping function that can represent several damping functions used in literatures with a few adjustable parameters. This universal damping function provides a unified formula that allows convenient comparison and flexible optimization in dispersion corrected DFT methods. Using the optimized universal damping functions and dispersion parameters, we develop dispersion correction methods for HF, B3LYP and PBE theories. We calculate the dispersive energies accurately for rare gas diatomic molecules and benzene dimers with an averaged error <4.1%.