Universiteit Leiden

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Ab initio molecular dynamics calculations on reactions of molecules with metal surfaces

Promotor: Prof.dr. G.J. Kroes

F. Nattino
28 oktober 2015
Thesis in Leiden Repository

Reactions on metal surfaces are of scientific interest due to the tremendous relevance of heterogeneous catalysis. Single crystal surfaces under controlled physical conditions are generally employed as a model for the real catalysts, with the aim of improving the fundamental understanding of the adsorption of molecules on metals. In this field, computer simulations have a high potential to help with interpreting experiments as they can provide an atomic-scale movie of a chemical process. The aim of this thesis has been to apply the ab initio molecular dynamics (AIMD) technique to the study of reactions on metal surfaces. The use of AIMD bypasses the need of pre-computing and fitting a potential energy surface, since the forces acting on the nuclei are calculated `on-the-fly' at each time step of the dynamics. The advantage is that statistically accurate reaction probabilities for small molecules on metal surfaces can be calculated including surface temperature effects and lattice recoil without introducing a priori dynamical approximations on the molecular degrees of freedom. Observables derived from the reaction probability, such as the sticking coefficient, the vibrational efficacy, and the rotational alignment parameter, have been calculated and compared to available experimental data for H2+Cu(111), N2+W(110) and CH4+Pt(111).