Six-dimensional potential energy surfaces for the dissociative chemisorption of HCl on rigid Ag(100) and Ag(110) surfaces.

Abstract

The dependence of reactivity on different facets of a surface is an interesting subject in dynamics at gas-surface interfaces. Here, we constructed new six-dimensional (6D) potential energy surfaces (PESs) for the dissociative chemisorption of HCl on rigid Ag(100) and Ag(110) surfaces, using the neural network method based on extensive density functional theory (DFT) calculations with the Perdew-Burke-Ernzerhof (PBE) functional, and compared the two PESs with the previously fitted PES of HCl/Ag(111). Time-dependent wave packet calculations show that the new PESs are very well converged with respect to the fitting procedure as well as to the number of DFT data points. The 6D dissociation probabilities for HCl initially in the ground rovibrational state decrease gradually for HCl/Ag(110), HCl/Ag(100), and HCl/Ag(111), consistent with the increasing barrier heights for the three reactions. The validity of the site-averaging approximation for HCl/Ag(110) does not hold well as compared with HCl/Ag(100) and HCl/Ag(111), in particular, at low kinetic energies, due to the strong steering effect this reaction exhibits if it is modeled with the semilocal PBE functional, which results in a low reaction barrier and a deep physisorption well.