Molecular Dynamics modeling of O(2)/Pt(111) gas-surface interaction using the ReaxFF potential

P Valentini and TE Schwartzentruber and I Cozmuta, 27TH INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS, 2010, PTS ONE AND TWO, 1333, 510-515 (2011).

DOI: 10.1063/1.3562699

We studied adsorption dynamics of O(2) on Pt(111) using Molecular Dynamics (MD) simulations with the ab initio based reactive force field ReaxFF. We found good quantitative agreement with the experimental data at low incident energies. Specifically, our simulations reproduce the characteristic minimum of the trapping probability at kinetic incident energies around 0.1 eV. This feature is determined by the presence of a physisorption well in the ReaxFF Potential Energy Surface (PES) and the progressive suppression of a steering mechanism as the translational kinetic energy (or the molecule's rotational energy) is increased. In the energy range between 0.1 eV and 0.4 eV, the sticking probability increases, similarly to molecular beam sticking data. For very energetic impacts (above 0.4 eV), ReaxFF predicts sticking probabilities lower than experimental sticking data by almost a factor of 3, due to an overall less attractive ReaxFF PES compared to experiments and DFT.

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