First Principles Modeling of Dissociative Adsorption at Crystal Surfaces: Hydrogen on Pt(111)

Multiscale simulation has the potential of becoming the new modeling paradigm in chemical sciences. An important class of multiscale models involves the mapping of a finer scale model into an approximate surface that is used by a coarser scale model. As a specific example of this class we present the case of the adsorption dynamics of diatomic molecules on single crystal catalyst surfaces. The prototype system studied is the dissociative adsorption of H₂ on Pt(111). The finer scale model consists of density functional theory (DFT) periodic slab calculations that provide a small dataset for training an atomistic scale potential energy surface. The coarser scale model uses a semi-classical molecular dynamics (MD) algorithm to obtain the sticking coefficient as a function of the incident energy. Comparison to experimental data and published simulation work is presented. Finally, major challenges in multiscale modeling of chemical reactivity in coupled DFT/MD simulations are discussed, specifically the need for a systematic method of assessing the accuracy of the coarse graining process.