【计算材料学】C掺杂和外电场对电子结构和光学性能的影响
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离散傅里叶变换法
DFT study for combined influence of C-doping and external electric field onelectronic structure and optical properties of TiO2(001) surface
C掺杂和外电场对TiO2（001）表面电子结构和光学性质影响的DFT研究
Authors: Cuihua Zhao, Dewei Huang and Jianhua Chen*
Volume 4, Issue 3, Pages 247-255
The electron structure and optical properties of C-TiO2 (001) surface under external electric field were studied by DFT method.
本文采用DFT方法研究了外电场下C-TiO2（001）表面的电子结构和光学性质。
After carbon doping, a new impurity level is introduced in the bandgap region of TiO2 (001) surface, and leads to the decrease of band gap, contributing to the shift of optical absorption to the visible region.
碳掺杂后，在TiO2（001）表面的带隙区域引入新的缺陷能级，导致带隙减小，有助于光吸收向可见光区域移动。
When external electric field is applied across the C-TiO2 (001) surface, the band gap is further reduced with the increase of the electric field intensity from 0.1 eV to 0.5 eV.
当在C-TiO2（001）表面上施加外部电场时，随着电场强度从0.1eV增加到0.5eV，带隙进一步减小。
The electric field over 0.5 eV induces the electronic polarization. The spin-up bands show a gap, while spin-down electrons correspond to a metallic state. The energy gap of spin-up band decreases with increasing the electric field from 0.7 eV to 1.0 eV.
当电场超过0.5 eV时会引起电子极化，自旋向上的带出现带隙，而自旋向下的电子对应于金属态。随着电场从0.7 eV增加到1.0eV，自旋向上的带隙减小。
The optical absorption of C-TiO2 (001) shifts to long wavelength compared with pure TiO2 (001).
与纯TiO2（001）相比，C-TiO2（001）的光学吸收向长波长方向移动。电场使光吸收进一步发生红移。
The electric filed make the optical absorption red-shift further, and the shift increases with an increase of the electric field, especially in the range of 0.7 eV–1.0 eV.
并且随着电场的增加，特别是在0.7eV-1.0eV的范围内，偏移会相应增加。
The results show that the combined effect of carbon doping and electric field can enhance the photocatalytic activity of TiO2 (001) surface in visible region.
结果表明，碳掺杂和电场的协同作用可以提高TiO2（001）表面在可见光区的光催化活性。
文中部分图片：
TiO2掺杂C表面模型
Fig. 2. Surface models of C-doped TiO2 (001), side view (a); top view (b).
TiO2掺杂C前后能带结构
Fig. 3. Band structure of TiO2 (001) (a) and C-TiO2 (001) (b).
O-Ti1键和C-Ti1键的电子密度
Fig. 6. Electron density difference of O-Ti1 bond for TiO2 (001) (a) and C-Ti1 bond for C-TiO2(001) (b) surface.
C掺杂TiO2在不同电场强度下的能带结构
Fig. 7. Band structure of C-TiO2 (001) with different electric fields. (a) 0.1 eV, (b) 0.3 eV, (c) 0.5 eV, (d) 0.7 eV, (e) 0.9 eV and (f) 1.0 eV. (Left shows spin-up band; Right shows spin-down band in (c), (d), (e) and (f)).
C掺杂TiO2在不同电场强度下的态密度
Fig. 8. DOSs of C-Ti1 bond for C-TiO2 (001) with different electric fields. (a) 0.1 eV, (b) 0.3 eV,b(c) 0.5 eV, (d) 0.7 eV, (e) 0.9 eV and (f) 1.0 eV.
C掺杂TiO2在不同电场强度下的光吸收系数
Fig. 10. Optical absorption of C-TiO2 (001) with different electric fields (a) and drawing of partial enlargement (b).
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