钴掺杂锐钛矿二氧化钛能带结构的第一性原理计算

First-Principles Calculation on the Band Structure of Co-Doped Anatase TiO_2

基于第一性原理的密度泛函理论,利用平面波超软赝势方法计算了纯锐钛矿相TiO2及Co掺杂TiO2的晶体结构、带隙、态密度及其光吸收系数。结果表明:掺杂能级的形成主要是Co的3d轨道的贡献,Co的3d轨道分别参与了价带和导带的组成,形成了杂化轨道,并且在价带和导带之间形成了新的杂质能级,缩小了带隙;Co掺杂使TiO2的光吸收系数阈值发生红移(>400nm),并在可见光区表现出一定程度的吸收。

The crystal structure, band gap, density of states and optical absorption coefficient of pure anatase ＂riO2 and cobalt （Co） doped anatase TiO2 were calculated by a plane-wave ultrasofi pseudopotential method based on the density functional theory of the first-principles. The results show that the formation of doping level is mainly contributed to 3d orbital of Co, which involves in the formation of the valence band and conduction band, leading to the formation of hybrid orbital. An impurity level appears between valence band and conduction band, reducing the band gap. The Co-doped TiO2 exhibited some absorptions in the visible light region and its optical absorption threshold shifted towards the long wavelength at 〉400 nm.