CeO2的晶格动力学性质和热输运性质的第一性原理计算

The Lattice Dynamical Properties and Thermal Transport Properties of CeO2：a first-principle study

摘要:

本文采用基于密度泛函理论的有限位移法和玻尔兹曼方程,计算了CeO₂的晶格动力学性质、热力学性质和热输运性质,计算结果和实验结果基本符合。通过分析CeO₂所有声子模式的振动频率、Grüneisen系数和散射率,揭示了光学声子对增强晶格振动的非简谐性和声子散射率所起的重要作用。此外,还计算了不同自由程的声子模式对热导率的贡献,发现CeO₂的晶格热导率主要由声子自由程在1~10 nm之间的声子所贡献。

Abstract:

The lattice dynamics, thermodynamic properties and thermal transport properties of CeO₂ are calculated by the finite displacement method and the Boltzmann equation based on density functional theory. The calculated results are in good agreement with the corresponding experimental results. The important role of optical phonons in enhancing the lattice anharmonicity and phonon scattering rates is revealed by analyzing the vibration frequency, Grüneisen coefficient and scattering rate of all phonon modes. Moreover, by calculating the relationship between the cumulative lattice thermal conductivity and the phonon free path, it is found that the thermal conductivity of CeO₂ is mainly contributed by phonons with a phonon free path between 1 and 10 nm.