First Principles Study On Electronic And Optical Properties Of TiO₂ Polymorphs

Based on density functional theory first-principles calculations methods can simulate the material structure and can calculate various physical and chemical properties of materials, so that we can thoroughly understand the material phenomena and characteristics of various types from macro to micro scale. And the first principles method can also predict a variety of new materials and its performance, providing the theoretical foundation and guidance to prepare and design material.TiO₂ is a very important semiconductor material with wide band gap, mainly including three crystal structures of anatase, rutile and brookite. TiO₂ has a high catalytic activity, good stability, non-toxic to humans and low cost, is an ideal semiconductor photocatalyst, which is widely used in the field of renewable energy and environmental protection. In recent years, scientists had researched doping TiO₂, but there are not systematic researchs on electrical properties, optical properties of the three main TiO₂.In this paper, we had studied systematically geometry, electronic structure and optical properties of the TiO₂ polymorphs. This thesis is divided into five chapters. The first chapter introduces the computational materials science and its research progress, the recent application of the first principle calculation method in materials science; also describes the basic structure, performance of TiO₂ and its applications. The second chapter introduces the first-principles calculation. The third chapter clarifies electronic structure through optimizing geometry of TiO₂. Chapter IV describes the optical properties of TiO₂. Chapter V of this paper summarized and pointed out that in theory there is still to be resolved.The intrinsic links between the electronic structures and the optical properties of the TiO₂ polymorphs had been revealed through this systematic theoretical studies, and it help us understand clearly the relationship and the law between the electronic structure and spectral absorption of TiO₂, which can provide theoretical basis for further study of TiO₂.