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arXiv 2106.09137cond-mat.mtrl-sci
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考虑电子-空穴相互作用的LiCoO2的光学响应和能带结构

Optical response and band structure of LiCoO2 including electron-hole interaction effects

Santosh Kumar Radha, Walter R. L. Lambrecht, Brian Cunningham, Myrta Grüning, Dimitar Pashov, Mark van Schilfgaarde

摘要:

在不同的近似水平下研究了LiCoO $_2$的光学响应函数和能带结构,从广义梯度近似(GGA)中的密度泛函理论(DFT)到准粒子自洽QS $GW$($G$为格林函数,$W$为屏蔽库仑相互作用),没有和有梯形图(QS $G\hat W$)和Bethe Salpeter方程(BSE)方法。QS $GW$方法被发现强烈高估的带隙和电子空穴或激子的影响被发现是重要的。它们使准粒子能隙仅减小11%,但吸收的最低能量峰是激子的。分析了不同带间跃迁的贡献以及激子与带间跃迁的关系。激子被发现是强烈本地化。实验数据的比较。

英文摘要:

The optical response functions and band structures of LiCoO$_2$ are studied at different levels of approximation, from density functional theory (DFT) in the generalized gradient approximation (GGA) to quasiparticle self-consistent QS$GW$ (with $G$ for Green's function and $W$ for screened Coulomb interaction) without and with ladder diagrams (QS$G\hat W$) and the Bethe Salpeter Equation (BSE) approach. The QS$GW$ method is found to strongly overestimate the band gap and electron-hole or excitonic effects are found to be important. They lower the quasiparticle gap by only about 11~\% but the lowest energy peaks in absorption are found to be excitonic in nature. The contributions from different band to band transitions and the relation of excitons to band-to-band transitions are analyzed. The excitons are found to be strongly localized. A comparison to experimental data is presented.

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