Semi-empirical molecular orbital calculations were performed using the macro-molecular orbital model to simulate the chemisorption and diffusion of oxygen and water on a graphite substrate. By comparing with previous calculations of this type it was shown that the method adopted for minimising edge effects by saturating dangling carbon bonds reproduced the surface properties adequately. Calculations using model substrates of 16 carbon and 10 hydrogen atoms and 24 carbon and 12 hydrogen atoms were performed. The chemisorption and diffusion of oxygen was studied by means of an equipotential contour map and the diffusion path and activation energy found. Less extensive calculations on water on graphite permitted suggesting the most probable diffusion path and activation energy. Sufficient results were obtained to allow some qualitative remarks to be concerning the inhibition of oxidation by an H2O mechanism.

Molecular Orbital Calculations of the Chemisorption and Diffusion of Oxygen and Water on a Graphite Substrate. Hayns, M.R.: Theoretica Chimica Acta, 1975, 39[1], 61-74