N掺杂钛酸锶的第一性原理研究

采用基于密度泛函理论的第一性原理平面波超软赝势计算方法，研究了N掺杂SrTiO3体系的几何结构和电子结构．通过分析N位于不同掺杂位置的SrTiO3晶格几何结构和电子态密度的变化发现：N掺杂SrTiO3使得其晶格结构发生畸变，但是N杂质原子位于不同掺杂位置导致其最近邻原子的相对位置变化存在明显差异；N掺杂SrTiO3不仅导致其费米能级进入到价带中，而且使得其光学带隙窄化，从而提高了其光吸收性能．但是，位于不同掺杂位置的N杂质原子2P态电子对N掺杂SrTiO3体系整体电子结构变化的贡献作用明显不同，从而导致其光学带隙窄化程度存在明显差异．

The Study of the First Principles of N-doped SrTiO3

The geometrical and electronic structures of N-doped SrTiO3 are investigated by using the first principles method with plane-wave ultra-soft pseudo-potentials based on the density functional theory. From the analysis of the geometry structure of crystal lattice and the electronic density of states for N- doped SrTiO3, it is found that N-doped SrTiO3 makes its lattice structure distortion, but the N-doped impurity atoms located in different locations results in the change of the relative position of its nearest neighbor atoms with significant differences; N-doped SrTiO3 has not only led to its Fermi into the valence band energy level, but also makes the optical band-gap narrowing, thereby enhancing the performance of its optical absorption. However, with respect to the different doping sites of N-impurity atom, its 2p electronic states significantly contributes to the changes of the whole electronic structure in different role, resulting in the narrowing of the optical band gap in different degrees.