SrTiO3材料中氧空位的密度泛函理论

计算了SrTiO3-δ（δ=0，δ=0．125）体系电子结构，分析了氧空位对SrTiO3晶体的价键结构、能带、态密度、分波态密度、差分电荷密度的影响。所有计算都是基于密度泛函理论（DFT）框架下的第一性原理平面波超软赝势方法。计算结果表明：当氧空位浓度δ=0．125时，空位在母体化合物SrTiO3中引入了大量的传导电子，费米能级进入导带，体系显示金属型导电性。由于空位掺杂，导带底附近的态密度发生了畸变，刚性能带模型不再适合描述SrTiO2.875体系。同时，在导带底附近距离费米能级0．3eV处引入了空位能级，这和实验测得的SrTiO3材料内中性氧空位的电离能约为0．4eV相符。此外，Mulliken布局分析、分波态密度和差分电荷密度分析表明，该空位能级主要由与其最近邻的两个Ti原子的3d电子态贡献，并且由该空位引入的导电电子大部分都局域在空位最近邻的两个Ti原子周围。最后，计算了三种典型平衡条件下SrTiO3晶体内中性氧空位的形成能。

Oxygen vacancies in SrTiO3 by density function theory

The electronic structure calculations including the Mulliken population analysis,band structure,density of states (DOS),partial density of states (PDOS) and electron density difference on SrTiO3-δwithδ=0 and δ=0.125 were performed by the first-principles calculation of plane wave ultrasoft pseudo-potential technology based on the density function theory (DFT).The calculated results revealed that due to the oxygen(O) vacancy electron doping,the Fermi level moved into conduction bands(CBs) for SrTiO3-δ with δ=0.125 and the system showed metallic behavior.There was a new defect level below the bottommost of CBs when one 0 vacancy was introduced.The 3d states of the two Ti atoms nearest to the vacancy made significant contribution to it.The electrons introduced by the O vacancy were largely localized on the two nearest Ti atoms.Furthermore,the formation energies of neutral O vacancy were calculated in three typical equilibrium conditions.