论文标题
对CA和MGS反射率的非谐作用：基于第一原理的研究
Anharmonic effects on the reflectivity of CaS and MgS: A first-principles based study
论文作者
论文摘要
我们采用基于密度功能理论的系统计算来模拟红外区域中CA和MG的反射率。我们表明，除了使用谐波近似建模外，精确的光谱描述还需要包含非谐作用。由于其概念上的简单性，CAS和MGS是明确考虑非骚扰性的绝佳系统，我们在此包括使用扰动接近，最多可以进行三频散射过程，以及对同位素疾病的考虑。从我们的第一原理计算中提取了所有物理量，例如天生的有效电荷和介电常数，用于计算Lorentz模型中反射率所必需的。为了验证我们预测的光学和横向模式以及反射率光谱，我们将它们与可用的实验结果进行了比较。我们发现总体一致是良好的，它支持在红外区域的光学性质建模中包含非谐项的重要性。
We employ systematic calculations based on density functional theory to model the reflectivity of CaS and MgS in the infrared region. We show that in addition to the modeling using the harmonic approximation, an accurate spectral description requires the inclusion of anharmonic effects. Due to their conceptual simplicity, CaS and MgS are excellent systems for the explicit consideration of the anharmonicity, which we include here using a perturbative approach up to three-phonon scattering processes, and the consideration of isotopic disorder. All physical quantities, such as Born effective charges and dielectric constant, necessary for the calculation of the reflectivity within the Lorentz model are extracted from our first-principles computations. To validate our predicted optical and transversal modes, and reflectivity spectra, we compare them to available experimental results. We find that the overall agreement is good, which supports the importance of the inclusion of anharmonic terms in the modeling of optical properties in the infrared region.
