Quasiclassical Trajectory Dynamics Study of Atomic Oxygen Collisions on an O-Preadsorbed Graphite (0001) Surface with a New Analytical Potential Energy Surface

A new flexible periodic LEPS potential energy surface (FPLEPS) based on density functional theory data is constructed for the interaction of atomic oxygen with an O-preadsorbed graphite (0001) surface over a C-C bridge. New ingredients were added to the usual expression of the FPLEPS in order to take into account the entrance barriers, molecular orientation, and morphology of the surface. A total of 563 DFT points were used to fit the Eley-Rideal (ER) reaction channel, achieving a root-mean-square deviation of 0.120 eV for energies lower than 1 eV over reactants. A quasiclassical trajectory (QCT) dynamics study has been performed at several initial conditions: collision energies (0.01 <= E-col <= 2.0 eV), incident angles (theta(v). = 0 degrees, 45 degrees), and surface temperatures (100 <= T-surf <= 900 K). Also quasithermal and hyperthermal (< E-col > = 5.2 eV) conditions were considered. Eley-Rideal reaction and O reflection were the main processes, keeping the formed O-2 molecules translationally and internally excited via the ER process. The calculated polar scattering angle distribution of hyperthermal atomic oxygen colliding onto a clean graphite surface matches better the experimental one for O/O-2 mixtures impinging on HOPG than those obtained for O colliding onto an O-preadsorbed surface.