Quasiclassical trajectory dynamics study of atomic oxygen collisions on an O-preadsorbed graphite (0001) surface with a new analytical potential energy surface

Abstract

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 ≤ Ecol ≤ 2.0 eV), incident angles (0, 45) and surface temperatures (100 ≤ Tsurf ≤ 900 K). Also quasithermal and hyperthermal ( = 5.2 eV) conditions were considered. Eley-Rideal reaction and O reflection were the main processes, remaining the formed O2 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/O2 mixtures impinging on HOPG than those obtained for O colliding onto an O-preadsorbed surface.