镧系元素掺杂TiO2的电子和光学特性的第一性原理计算
The electronic and optical characteristics of lanthanide doped TiO2 from first-principles calculation

基于密度泛函理论的第一性原理局部密度近似法，结合Hubbard U校正（LDA + U），研究了镧系元素掺杂的锐钛矿型TiO2的取代能、热力学电荷跃迁能级和光学性质。除La之外的所有镧系元素，在掺杂时向主带隙中引入杂质态。所得取代能表明了镧系元素掺杂TiO2的可行性。同时预测了最佳掺杂比例约为3％，由Ce、Nd、Sm、Gd或Tm掺杂引入的掺杂能级具有负U特性。另外，所得热力学跃迁能级预测了Lu在主带隙内不发生电荷跃迁。算出的光吸收系数表明镧系元素掺杂可使TiO2具有可见光吸收性能。
A method based on density functional theory using first principles was applied to calculate the charge transition levels and optical properties of lanthanide doped anatase phase TiO2, along with the Hubbard U correction. It is found that apart from La element, all lanthanides introduce impurity levels in the bandgap of TiO2 through doping. The obtained substitutional energy showed the possibility of lanthanide doping into TiO2. The optimal doping concentration is around 3% and the Ce, Nd, Sm, Gd or Tm doped TiO2 introduces impurity levels with negative U characteristics. Moreover, the obtained charge transition level proved that no charge transition could take place in the host bandgap. The obtained optical absorption coefficients proved that lanthanide doped anatase phase TiO2 is capable of absorbing visible light irradiation.