Ab initio many-body Green's function calculations of optical properties of LiF at high pressures
Ab initio many-body Green's function calculations of optical properties of LiF at high pressures
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DOI：
10.1103/physrevb.92.245117
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发表时间：
2015-12
影响因子：
3.7
通讯作者：
C. Spataru;L. Shulenburger;L. Benedict
中科院分区：
文献类型：
--
作者：
C. Spataru;L. Shulenburger;L. Benedict
我们用密度泛函理论(DFT)对LiF长波介电函数的实部和虚部进行了准粒子自能Bethe-Salpeter计算。虽然光学吸收光谱在光学带隙上方显示出明显的压力依赖特征，但远低于带隙的折射率显示出与DFT计算和实验中所看到的相同的趋势：大致随密度线性增加。这一增加并不是由于带隙的减少，而是由于振子强度的增加，这抵消了带隙的较小增加。我们的计算还表明，较高相的折射率(对于可见光和近紫外光)应该与(环境晶体)相的折射率非常接近。在动态压缩实验中使用LiF作为窗口材料的研究人员可能会对这些发现感兴趣。
We present density functional theory (DFT)quasiparticle self-energyBethe-Salpeter calculations of the real and imaginary parts of the long-wavelength dielectric function of LiF between ambient pressure andMbars. While the optical absorption spectrum is predicted to show dramatic pressure-dependent features above the optical gap, the index of refraction well below the gap is shown to exhibit the same trends as that seen in both DFT calculations and experiment: a roughly linear increase with density. This increase does not result from a decrease in the band gap, but rather follows from the increase in oscillator strength which counteracts a smaller increase in band gap with. Our calculations also suggest that the index of refraction (for visible and near-UV light) of the higher-phase should be quite close to that of the(ambient crystalline) phase. These findings may be of interest to researchers who use LiF as a window material in dynamic compression experiments.