Molecular dynamics simulation of O2 sticking on Pt(111) using the ab initio based ReaxFF reactive force field

Abstract

The molecular dynamics technique with the ab initio based classical reactive force field ReaxFF is used to study the adsorption dynamics of O(2) on Pt(111) for both normal and oblique impacts. Overall, good quantitative agreement with the experimental data is found 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 when increasing the translational kinetic energy (or the molecule's rotational energy) because of steric hindrance. In the energy range between 0.1 and 0.4 eV, the sticking probability increases, similar 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 density functional theory. For oblique impacts, the trapping probability is reduced by the nonzero parallel momentum because of the PES corrugation and does not scale with the total incident kinetic energy. Furthermore, our simulations predict quasispecular (slightly supraspecular) distributions of angles of reflection, in accordance with molecular beam experiments. Increasing the beam energy (between 1.2 and 1.7 eV) causes the angular distributions to broaden and to exhibit a tail toward the surface normal because molecules have enough momentum to get very near the surface and thus probe more corrugated repulsive regions of the PES.

Cutting a chemical bond with demon's scissors: Mode- and bond-selective reactivity of methane on metal surfaces

“…The use of such a reaction specific RFF allowed for obtaining, from classical trajectory calculations, sticking probabilities in good overall agreement with previous state-of-the-art theoretical results and experiments. Interestingly, only a few months later, Valentini et al [51] also reported classical trajectory MD results in good agreement with molecular beam experiments for O 2 /Pt(111), using a ReaxFF PES specifically trained to reproduce a large set of O/Pt(111) and O 2 /Pt(111) DFT interaction energies (including molecularly adsorbed states and dissociation barriers) [51].…”

Atomic-scale simulations of reactive oxygen plasma species interacting with bacterial cell walls

“…Forces on the atoms are derived from the ReaxFF potential [18]. This force field has now been successfully applied to describe nearly half of the periodic table of the elements and their compounds, including hydrocarbons [18,37], metals and metalcatalyzed reactions [38,39], metal oxides [40], metal hydrides [41] and silicon and silicon dioxide [42][43][44]. Recently, it has also been used for organic molecules, such as glycine [19,45], as well as for complex molecules, such as DNA [46].…”

The ReaxFF reactive force-field: development, applications and future directions

“…This issue is especially apparent in low-density gas phase simulations, where EEM-ReaxFF predicts small, but certainly nonzero, charges on isolated molecular species, which significantly affects accommodation coefficients. 135 In simulations of dense systems, unrealistic charge-transfer may also occur (e.g., between two dielectric phases with a different intrinsic electronegativity). To ameliorate this issue, we have recently incorporated atom-condensed Kohn-Sham DFT approximated to second order (ACKS2) in ReaxFF.…”