高极性Pb（Ti $_{1-x}$ Ni $_{x}$）O $_{3-x}$固溶体的Post密度泛函理论研究：阳离子排列对带隙的影响
Post density functional theoretical studies of highly polar semiconductive Pb(Ti$_{1-x}$Ni$_{x}$)O$_{3-x}$ solid solutions: The effects of cation arrangement on band gap
摘要：
我们采用传统的密度泛函理论（DFT）和后DFT方法，包括局域密度近似+Hubbard $U$（LDA+ $U$），PBE 0和自洽$GW$，研究了Ni取代的PbTiO $_{3}$（Ni-PTO）固溶体的电子性质.我们发现LDA计算产生不合理的能带结构，特别是对于含有不间断NiO $_{2}$层的Ni-PTO固溶体。精确处理过渡金属氧化物（如Ni-PTO）中的局域态需要后DFT方法。还研究了$B$位Ni/Ti阳离子有序性。$B$位点阳离子排列改变了Ni和O之间的键合，因此强烈影响Ni-PTO的带隙（$E_{\rm g}$）。我们预测，镍PTO固溶体应该有一个直接的带隙在可见光的能量范围内，与父母PbTiO $_{3}$类似的偏振。这种性能的组合使得Ni-PTO固溶体成为太阳能转换装置的有希望的候选材料。
英文摘要：
We use a combination of conventional density functional theory (DFT) and post-DFT methods, including the local density approximation plus Hubbard $U$ (LDA+$U$), PBE0, and self-consistent $GW$ to study the electronic properties of Ni-substituted PbTiO$_{3}$ (Ni-PTO) solid solutions. We find that LDA calculations yield unreasonable band structures, especially for Ni-PTO solid solutions that contain an uninterrupted NiO$_{2}$ layer. Accurate treatment of localized states in transition-metal oxides like Ni-PTO requires post-DFT methods. $B$-site Ni/Ti cation ordering is also investigated. The $B$-site cation arrangement alters the bonding between Ni and O, and therefore strongly affects the band gap ($E_{\rm g}$) of Ni-PTO. We predict that Ni-PTO solid solutions should have a direct band gap in the visible light energy range, with polarization similar to the parent PbTiO$_{3}$. This combination of properties make Ni-PTO solid solutions promising candidate materials for solar energy conversion devices.
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