SrNbO$_3$中的八面体畸变：揭示结构-性能关系
Octahedral distortions in SrNbO$_3$: Unraveling the structure-property relation
AI总结：
本文通过DFT和DFT+DMFT计算研究SrNbO$_3$中八面体倾斜与应变的关系，揭示同相与反相倾斜竞争为调控热电和光学性能提供了新自由度。
摘要：
铌酸锶作为一种透明导体以及关联狄拉克半金属的可能实现形式，已引发了广泛关注。本研究以晶格参数作为可调控制变量，利用密度泛函理论计算绘制了八面体倾斜的能量景观。我们发现，双轴压缩应变会诱导围绕面外轴的倾斜，而拉伸应变则诱导围绕两个面内轴的倾斜。对于压缩应变，两种相互竞争的畸变结构在其电子结构中表现出费米能级以上的半狄拉克色散。我们的密度泛函理论计算结合动力学平均场理论（DFT+DMFT）揭示，动力学关联效应将这些类半狄拉克锥向费米能量下移。更广泛地，我们的研究表明，SrNbO$_3$中同相倾斜与反相倾斜之间的竞争提供了一个新的自由度，可用于调控热电性能和光学性能。我们展示了倾斜角度和倾斜模式如何通过能带结构的变化反映在塞贝克系数和等离子体频率的行为中。
英文摘要：
Strontium niobate has triggered a lot of interest as a transparent conductor and as a possible realization of a correlated Dirac semi-metal. Using the lattice parameters as a tunable knob, the energy landscape of octahedral tilting was mapped using density functional theory calculations. We find that biaxial compressive strain induces tilting around the out-of-plane axis, while tensile strain induces tilting around the two in-plane axes. The two competing distorted structures for compressive strain show semi-Dirac dispersions above the Fermi level in their electronic structure. Our density functional theory calculations combined with dynamical mean field theory (DFT+DMFT) reveals that dynamical correlations downshift these semi-Dirac like cones towards the Fermi energy. More generally, our study reveals that the competition between the in-phase and out-of-phase tilting in SrNbO$_3$ provides a new degree of freedom which allows for tuning the thermoelectric and optical properties. We show how the tilt angle and mode is reflected in the behavior of the Seebeck coefficient and the plasma frequency, due to changes in the band structure.
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