利用高多极阶数从晶格动力学重构压电材料中的声速
Using high multipolar orders to reconstruct the sound velocity in piezoelectrics from lattice dynamics
摘要：
声子能带结构的信息对于预测材料的许多热力学性质，如热输运系数是至关重要的。高精度的声子色散曲线，原则上，可以计算密度泛函微扰理论（DFPT）的框架。然而，在压电材料的情况下，成熟的技术可能会遇到麻烦（甚至灾难性地失败），其中声学分支几乎不能再现物理上正确的声速。在这里，我们确定了原子之间高阶多极相互作用的罪魁祸首，并演示了一个有效的程序来解决上述问题。我们的策略大大提高了压电晶体微扰晶格动力学计算的预测能力，并可直接实现高通量生成材料数据库。
英文摘要：
Information over the phonon band structure is crucial to predicting many thermodynamic properties of materials, such as thermal transport coefficients. Highly accurate phonon dispersion curves can be, in principle, calculated in the framework of density-functional perturbation theory (DFPT). However, well-established techniques can run into trouble (or even catastrophically fail) in the case of piezoelectric materials, where the acoustic branches hardly reproduce the physically correct sound velocity. Here we identify the culprit in the higher-order multipolar interactions between atoms, and demonstrate an effective procedure that fixes the aforementioned issue. Our strategy drastically improves the predictive power of perturbative lattice-dynamical calculations in piezoelectric crystals, and is directly implementable for high-throughput generation of materials databases.
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