On the performance of van der Waals corrected-density functional theory in describing the atomic hydrogen physisorption on graphite

► Current density functional theory (DFT) approaches are unable to describe properly the weak van der Waals (or dispersion) interactions such as those present in H-graphite physisorption. ► The incorporation of an empirical dispersion term leads to a significant improvement in the optimized distances, physisorption energies and minimal diffusion barriers. ► DFT + vdW approximation could be an alternative and powerful tool for the study of diffusion or chemical reactions of physisorbed species, such as those present on the surface of dust grains in the cold interstellar medium.