中文摘要：

采用基于密度泛函理论的第一性原理平面波超软赝势方法研究了纯锐钛矿相TiO2,S、Mn分别单掺杂及共掺杂TiO2的晶体结构、杂质形成能、电子结构、光学性质和带边位置。计算结果表明,掺杂后TiO2的晶格发生畸变,原子间的键长、原子的电荷量以及晶体体积都发生变化,导致晶体中八面体偶极矩增大,从而有利于光生电子-空穴对的分离;S掺杂在TiO2的价带顶部形成杂质能级,Mn掺杂在TiO2的导带下方和费米能级附近形成杂质能级,共掺杂后TiO2禁带宽度变窄,光学吸收带边发生红移,TiO2在可见光区有明显的吸收;同时S、Mn共掺杂后TiO2的带边位置发生了明显变化,氧化还原能力增强,有利于提高光催化效率

英文摘要：

The crystal structure,impurity formation energy,electronic structure,optical properties and band edge position of sulfur and manganese codoped anatase TiO2 were studied by using the plane-wave ultrasoft pesudopotentials method based on density functional theory.The calculated results show that the octahedral dipole moments in TiO2 increase due to the changes in lattice parameters,bond length and charges on atoms,which was very effective for the separation of photoexcited electron-hole pairs and the improvement of the photocatalytic activity of TiO2.The analysis from the band structures,density of states show that there are three new impurity bands in the top of the valence band in S-doped TiO2,two impurity bands below the conduction band and three impurity bands near the Fermi level in Mn-doped TiO2.On the base of the synergistic reaction of S and Mn,S-Mn codoped anatase TiO2 would lead to the narrowing of the band gap,the red shift of absorption wavelength and the increase of absorption coefficients in visible-light region.For S-Mn codoped TiO2,the band edge position of anatase TiO2 changes significantly,which can enhance the redox capacity and improve the efficiency of the photocatalytic.