DFT investigation of the adsorption of atomic hydrogen on a cluster-model graphite surface

The H-graphite interaction is studied for the first time in the framework of density functional theory. A coronene-like model of the (0001) graphite surface is considered. LSD and LSD+GGA results are presented for both a planar substrate and for considering substrate relaxation. Two adsorption regions separated by a barrier are found: a physisorption region around 3 إ from the surface and a chemisorption region around 1.5 إ. The former is site-independent and compatible with a high mobility of the H atoms parallel to the surface. The latter is located exclusively on top of a carbon atom and requires a significant surface relaxation.