The Microscopic Dynamics Of The Atomic And Diatomic Molecules In The Transition Metal Surface Adsorption

Solid catalysts and the reactions promoted by them have received considerable attention during the past decades. Especially, interactions between atoms, molecules and metal surfaces have been widely studied. Employing two kinds of semi-empirical methods-the 5-MP and the extended LEPS potential, we selected a few typical atoms (H, O, N) and molecules (Ni, CO), studied their dynamic characteristics of dissociated adsorption, diffusion on transition metals (Rh, Fe, Pt) and gained good results. The main characteristic of the present work is as follows:1. The interactions between atoms and metal surfaces are solved by 5-MP In the present work, we make an assumption called "surface frozen approximation",take account of the orientation affect of d electrons of transition metals, and construct the theoretical model-5-MP. Because this model is a semi-empirical method, we must employ experimental data to simulate the five parameters. As long as we can reproduce simultaneously the experimental data of three low-index surfaces by 5-MP, the five parameters can then be used to deal with the interaction between atom and stepped surface that is formed by low-index surface. So, the 5-MP is independent on the surface-cluster structures. Using this method, we reproduce the dynamic characteristics of above atom-surface systems such as the adsorption sites, the adsorption geometry, the binding energy and the eigenvibration etc... we also appraise some unreasonable experimental data and predict some important information that hasn't been observed.2. The interactions between diatomic molecules and metal surfaces are solved by the extended LEPS potentialTo construct the extended LEPS, three pair-potentials are needed: we use the 5-MP that is mentioned above as the bonding pair-potential between two atoms and metal surface cluster and employ the Morse potential as the one between two atoms. In our work, we must select three Sato parameters. Because the three Sato parameters are suitable simultaneously to three low-index surfaces, the extended LEPS potential constructed by us is also independent on the surface-cluster structures. Using this method, we performed systematic study for CO adsorption on Pt low-index surfaces; we also performed study for NI dissociated adsorption on Fe low-index surfaces, reproduced the experimental data on three low-index surfaces, and put forward a detailed indirectdissociation mechanism for Na: δ- state γ→state→α→state→ β→state →βstate.