Density Functional Theory Study Of Oxygen Adsorption On Fe(100) And Rh(100) Surface

In this dissertation, the dissociation processes of oxygen molecule on Fe(100) surface, the adsorption and diffusion of oxygen atom on the same surface are theoretically investigated by means of the density functional theory (DFT). Also, the adsorption of O atom on Rh(100) surface are researched, and the results are discussed in detail. The main results are as follows:1. Quantum Chemical Study of the dissociation of oxygen molecule on Fe (100) surfaceThe dissociations of O₂ molecule on different adsorption sites at Fe (100) surface are calculated using the density functional method. From the analysis of four possible dissociate modes of O₂ molecule, it's clear that the dissociation of O₂ molecule on Fe (100) surface is easily and the final geometry is the adsorption of O atom on Fe (100) surface. The energy barrier of the process is low.2. Quantum Chemical Study of the adsorption of oxygen atom on Fe(100) surfaceThe adsorption of O atom on on-surface adsorption sites and sub-surface sites are calculated using the density functional methods, respectively. The results indicate that there are stable adsorption sites of the O atom on Fe (100) on-surface sites and sub-surface sites. The most stable adsorption sites of O atom on on-surface are 4F and 2F site, and on sub-surface are tetrahedral-like and octahedral-like site. The existence of sub-surface O atom enhances the relaxation of the neighbor Fe layers. The O atom locates at regular tetrahedral (or regular octahedral) site when the O atom is under the third Fe layer, which indicates the O atom is inside of the bulk. 3. Quantum Chemical Study of the diffusion of oxygen atom on Fe (100) surfaceThe diffusion of O atom among the different on-surface adsorption sites and the different sub-surface sites are researched, respectively, using the density functional methods. In addition, the diffusion of O atom from on-surface adsorption sites into sub-surface ones is also investigated at the same theoretical level. In order to make clear the mechanism, the diffusion pathway of O atom from Fe (100) surface into bulk is studied. The results indicate that the O atom is inclined to diffusion sub-surface site after the O atom adsorbed on on-surface sites. In the whole diffusion process, the highest energy barrier is 1.813eV.4. Quantum Chemical Study of the adsorption of oxygen atom on Rh(100) surfaceThe first-principle studies on the adsorption of O on Rh (100) surface are performed by the density functional theory. At different coverage, the electronic property, structure parameters and the adsorption energy are investigated for the different adsorption sites. The calculated results suggested that there is a stable adsorption configuration between the O and the Rh (100) surface. The highest adsorption energy is 2.53eV. The analysis of density of states of O atom is performed, and we conclude that the adsorption of O atom on Rh (100) surface is mainly caused by the interactions between the 2p orbital of the O atom and the 4d orbital of metal.