Chemical Dynamics Simulations of Water Collisions with a Graphite Surface

This study presents a comprehensive analysis of the scattering dynamics of D₂O molecules on highly oriented pyrolytic graphite surfaces using molecular dynamics simulations. The MD simulation protocols are validated against experiments, which contain only in-plane scattering [Gibson, K. D., J. Chem. Phys. 2024, 160(1), 194705.10.1063/5.0205984]. However, the in-plane results fail to capture the overall dynamics due to the significant contribution of out-of-plane scattering, which is difficult to measure. In this study, our simulations consider both in- and out-of-plane scatterings and show that the intermediate incident angle (∼40°) minimizes water–HOPG interaction. By analyzing the relation between the number of internal turning points, we relate the incident angle to the rate of thermalization of the scattered-off molecules. Our findings highlight the capability of MD simulations to model complex gas–surface interactions that are difficult to capture experimentally, offering an effective and accurate method for future studies across a wider range of energies, temperatures, surfaces, and multimolecule interactions.