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基于密度泛函理论的从头算方法,以锐钛矿TiO_2为研究对象,利用计算机模拟技术分析了S掺杂TiO_2的电子结构。用广义梯度近似法对优化后的理论模型进行单电子能量计算,到完整的和掺S的TiO_2晶体能带、总态密度(TDOS)以及分态密度(PDOS)图。分析了光学性质中的介电函数、吸收系数值。计算结果表明:TiO_2经掺杂后带隙变窄,掺杂后体系的介电函数向低能方向移动,具有优异的介电性能,掺杂体系的吸收边红移。S原子取代TiO_2中的O原子后,价带上方的杂质能级峰强较大,电子在该杂质能级上存在几率较大。在可见光催化实验中,可形成光生电子-空穴的捕获势阱,减小电子与空穴的复合几率,进而提高光催化效果。
Ab initio method based on density functional theory and anatase TiO 2 as the research object, the electronic structure of S-doped TiO_2 was analyzed by computer simulation. The generalized gradient approximation method is used to calculate the single electron energy of the optimized theoretical model, and the complete and doped T 2 crystal energy band, total state density (TDOS) and density of states (PDOS) diagrams. The dielectric function and absorption coefficient in optical properties were analyzed. The calculated results show that the band gap of TiO_2 becomes narrower after doping, and the dielectric function of the doped system moves to the low energy direction, which results in excellent dielectric properties and absorption edge red shift of the doped system. When S atom replaces O atom in TiO_2, the peak of the impurity level above the valence band is larger and the electron is more likely to exist on the impurity level. In the visible light catalytic experiment, the trapped potential well of photogenerated electron-hole can be formed, the recombination probability of electrons and holes can be reduced, and the photocatalytic effect can be further improved.