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

The atomic hydrogen physisorption on graphite was studied using the hydrogen–coronene model system and the van der Waals corrected-density functional theory (DFT + vdW). The results show that H preferentially occupies the hollow site. The adsorption energy at this site is calculated as 38.1 meV, in very good agreement with the available experimental measurements on a single graphite layer (39.2 ± 0.5 meV) and with reported MP2/aug-cc-pVDZ calculations (39.7 meV). The results suggest that, in DFT simulations, dispersion corrections should be considered in order to obtain accurate distances, adsorption energies and diffusion barriers in physisorption processes such as those occurring in the cold interstellar medium.