研究温度相关的多体相互作用对SnTe体电子结构和（001）表面态的影响
Investigating the effect of temperature dependent many-body interactions on bulk electronic structures and the robust nature of (001) surface states of SnTe
摘要：
最近，SnTe由于其非平凡的拓扑性质和生态友好的热电应用而受到关注。用密度泛函理论和量子化学方法研究了该化合物的电子结构和热力学性质。用PBESol和$G_0W_0$方法计算的带隙与实验值符合较好，而mBJ方法低估了带隙. Sn（Te）5 $p$轨道的全屏蔽库仑相互作用（$W$）估计值为$\sim$ 1.39（$\sim$ 1.70）eV。$W$的频率相关性质表明，该化合物的相关强度相对较弱，因此可以用全$GW$多体技术研究其激发电子态.等离子体激元激发被认为是重要的，在理解这种频率依赖性$W$。为了描述实验声子模，考虑了用非分析项修正的长程库仑力。温度依赖的电子-电子相互作用（EEI）随着温度的升高而减小带隙。在300 K时的带隙值为$\sim$ 161 meV。计算了W-L- $Γ$方向上电子态的温度寿命。这项工作表明，EEI是重要的，以解释高温传输行为的SnTe。我们还探讨了通过镜像和时间反演对称性保护（001）表面态的可能性。预计这些表面状态对点和线缺陷是鲁棒的。
英文摘要：
Recently, SnTe has gained attention due to its non-trivial topological nature and eco-friendly thermoelectric applications. We report a detailed temperature dependent electronic structure and thermodynamic properties of this compound using DFT and GW methods. The calculated values of bandgaps by using PBEsol and $G_0W_0$ methods are found to be in good agreement with the experiment, whereas mBJ underestimates the bandgap. The estimated value of fully screened Coulomb interaction ($W$) for Sn (Te) 5$p$ orbitals is $\sim$1.39 ($\sim$1.70) eV. The nature of frequency dependent $W$ reveals that the correlation strength of this compound is relatively weaker and hence the excited electronic state can be properly studied by full-$GW$ many-body technique. The plasmon excitation is found to be important in understanding this frequency dependent $W$. In order to describe the experimental phonon modes, the long range Coulomb forces using nonanalytical term correction is considered. The temperature dependent electron-electron interactions (EEI) reduces the bandgaps with increasing temperature. The value of bandgap at 300 K is obtained to be $\sim$161 meV. The temperature dependent lifetimes of electronic state along W-L-$Γ$ direction are also estimated. This work suggests that EEI is important to explain the high temperature transport behaviour of SnTe. We have also explored the possibility of protecting the (001) surface states via mirror and time-reversal symmetry. These surface states are expected to be robust against the point and line defects.
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