标题： 极性材料红外介电函数预测的Green-Kubo公式与Lorentz模型之间的一致性 显示英文标题

标题： Consistency between the Green-Kubo formula and Lorentz model for predicting the infrared dielectric function of polar materials

摘要： 极性材料中红外介电函数的精确预测对于热学和光子学应用而言至关重要，但至今尚未明确两种主要方法——Green-Kubo公式与Lorentz模型是否能够提供统一的预测。 在这项工作中，我们以MgO和LiH作为典型实例，利用经验刚性离子模型（RIM）和机器学习势能（MLP），对这两种方法进行了详细的对比分析。 我们证明了传统的Lorentz模型无法捕捉Green-Kubo方法中固有的多声子吸收现象，而这一问题可以通过使用声子自能量作为通常线宽的一般化来解决。此外，在RIM中，需要在离子对红外响应的贡献中加入一个校正因子，以弥补电子极化效应，而这一效应已被MLP通过计算偶极矩时采用Born有效电荷所捕获。 因此，本基准研究不仅能够实现介电函数计算的交叉验证，还为极化动力学提供了机制上的见解。 显示英文摘要

摘要： Accurate prediction of infrared dielectric functions in polar materials is fundamental for thermal and photonic applications, yet it remains unexplored whether the two main methods, Green-Kubo formula and Lorentz model, can give unified predictions. In this work, we present a detailed comparison of these two approaches using MgO and LiH as prototypical cases employing both empirical rigid ion model (RIM) and machine learning potential (MLP). We demonstrate that the conventional Lorentz model fails to capture the multi-phonon absorption inherent in Green-Kubo method, which can be resolved via using the phonon self-energy as a generalization of the usual linewidth. In addition, with RIM, a correction factor is required in the ionic contribution to infrared response to account for the electronic polarization effect, which is yet captured by MLP using the Born effective charges for calculating dipole moment. The present benchmark study thus enables cross-validation of dielectric function calculations while providing mechanistic insights into the polarization dynamics.