The Electronic Structure Research Of Transition Metal Oxide Surfaces

In recent years, with the rapid progress of the computer technology and computing method, the computational physics plays an increasing important role in physical sciences. Because of its little dependence on experimental material and equipment, many researchers from all over the world favor using it to explore the secrets in materials. The first principles calculation, which is based on density functional theory, is one of the most important methods among the computational physics and has been widely used in computational simulation structure and materials design.In this paper, we employed first principle calculation to some different kinds of metal oxides to explore their crystal structure, magnetism, electrical conductivity and the relative stability of structure. The main work includes:1. The electronic structures and the stability of the low-index surface(001),(011) and(111) for MgO were investigated. We analyzed the stability of the MgO slab in equilibrium with an arbitrary oxygen environment. The density of states and the band structures of MgO slabs were calculated and compared with those of the bulk MgO. Our calculation results reveal that the stabilities of the surface vary with the change of O chemical potential. In addition, the MgO(001) and MgO(011) surfaces are semiconductors, which is similar to the bulk MgO, while the MgO(111) surface exhibits metallic property, which is different from that of the bulk MgO.2. The effect of oxygen vacancies on the electronic structures, magnetic properties and the stability of the SrTiO3(001) surface were investigated. The calculation results reveal that the stabilities of the proposed eleven surface models vary with the change of Sr and O chemical potential. As for the magnetic property, the with ferromagnetic, antiferromagnetic and paramagnetic states all exhibit in the eleven SrTiO3(001) models respectively. Furthermore, the Sr TiO3(001) slabs show metal, half-metal and semiconductor properties in different models, which are affected by the positions of oxygen vacancies.3. The electronic structures of Au(111)/NiO(111) interface based on the two models of NiO(111) surface were studied. The work of adhesion, relative stability and electronic properties of the Au(111)/NiO(111) interface were calculated by density functional theory(DFT). Through calculations, we find that the interface energies of the Ni-terminated and the O-terminated interface are independent of the oxygen chemical potential, while that of the oxidized interfaces are dependent linearly ongas O O? ??. At the same time, we predict that the oxidized interface model is more stable than the other interface models. Finally, the calculations of the electronic structure reveal that the Ni-terminated and the oxidized interfaces have anti-ferromagnetic properties, while the O-terminated interface exhibits ferromagnetic properties.