Ab Initio Simulations of the Kinetic Properties of the Hydrogen Monomer on Graphene

The understanding of the kinetic properties of hydrogen (isotopes) adatoms on graphene is important in many fields. The kinetic properties of hydrogen-isotope (H, D, and T) monomers were simulated using a composite method consisting of density functional theory, density functional perturbation theory, and harmonic transition state theory. The kinetic changes of the magnetic property and the aromatic π bond of the hydrogenated graphene during the desorption and diffusion of the hydrogen monomer were discussed. The vibrational zero-point energy corrections in the activation energies were found to be significant ranging from 0.072 to 0.205 eV. The results obtained from quantum mechanically modified harmonic transition state theory were compared with the ones obtained from classical-limit harmonic transition state theory over a wide temperature range. The phonon spectra of hydrogenated graphene were used to closely explain the (reversed) isotope effects in the prefactor, the activation energy, and the jump fr...