Modeling of the Dissociative Adsorption Probability of the H 2 -Pt(111) System Based on Molecular Dynamics

Abstract. Molecular Dynamics (MD) was used to simulate dissociative adsorption of a hydrogen molecule on the Pt(111) surface considering the movement of the surface atoms and gas molecules. The Embedded Atom Method (EAM) was applied to represent the interaction potential. The parameters of the EAM potential were determined such that the values of the dissociation barrier at different sites estimated by the EAM potential agreed with that of DFT calculation results. A number of MD simulations of gas molecules impinging on a Pt(111) surface were carried out randomly changing initial orientations, incident azimuth angles, and impinging positions on the surface with fixed initial translational energy, initial rotational energy, and incident polar angle. The number of collisions in which the gas molecule was dissociated were counted to compute the dissociation probability. The dissociation probability was analyzed and expressed by a mathematical function involving the initial conditions of the impinging molecule, namely the translational energy, rotational energy, and incident polar angle. Furthermore, the utility of the model was verified by comparing its results with raw MD simulation results of molecular beam experiments

Numerical analysis of gas flow in porous media with surface reaction

Abstract. Gas flow with surface reaction in porous media appears in various regions of engineering. In porous media with holes as small as a molecular mean free path, Kn of gas flow in the narrow channel is on the order of unity. Therefore, the direct simulation Monte Carlo (DSMC) method is suitable to solve transport phenomena in such kind of porous media. We perform 2D DSMC simulations of such a flow. The shape of narrow channel in porous media is complicated. To reduce complexity, we propose the simplification for porous structures by cubes and polyhedra. Results for the simplification by polyhedra agree well with the result obtained in the case without simplification. Results for the simplification by cubes also show good agreement with the result without simplification when surface reaction probability is modified