Npj Comput. Mater.: 天下武功，唯快不破—第一性原理输运计算

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Fig. 1 Carrier scattering.

来自英国华威大学工程学院的李圳博士、Patrizio Graziosi博士和Neophytos Neophytou教授，提出了密度泛函微扰理论结合形变势理论的计算策略，研究了半导体的电子-声子耦合和输运性质，实现了与完全第一性原理计算方法一致的准确度。

Fig. 2 Electron–phonon coupling matrix elements for Mg3Sb2.

作者基于电子-声子矩阵元推导声学、光学和谷间形变势，并考虑极性光学支声子和电离杂质散射，基于自主开发的开源玻尔兹曼输运软件ElecTra进行计算。以n型Mg₃Sb₂为例，阐述了如何应用在具有复杂能带结构的材料。与DFPT + Wannier方法相比，计算结果取得了极好的一致性，同时计算成本小于其10%。将同样的方法应用于Si，在准确度类似的情况下，计算成本小于其1%。

Fig. 3 Calculated scattering rates and transport properties for Mg3Sb2.

除了实现快速计算外，作者的方法还提供了准确性和灵活性：1）通过在特定能量和波矢下选择性地计算关键矩阵元，在重要的电子散射区域提供密集网格；2）明确了各个散射过程（声学、光学、谷内和谷间），提供了能带工程中有关多谷结构的关键信息。与最先进的完全第一性原理方法相比，该计算策略同时实现了高效、准确、灵活的输运计算。

Fig. 4 Comparison of computation time and accuracy in transport calculations.

Fig. 5 Comparison of intra-valley and inter-valley scattering in Mg3Sb2. 

该文近期发表于npj Computational Materials 10：9(2024)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。

Efficient first-principles electronic transport approach to complex band structure materials: the case ofn-type Mg₃Sb₂

Zhen Li, Patrizio Graziosi & Neophytos Neophytou 

We present an efficient method for accurately computing electronic scattering rates and transport properties in materials with complex band structures. Using ab initio simulations, we calculate a limited number of electron–phonon matrix elements, and extract scattering rates for acoustic and optical processes based on deformation potential theory. Polar optical phonon scattering rates are determined using the Fröhlich model, and ionized impurity scattering rates are derived from the Brooks-Herring theory. Subsequently, electronic transport coefficients are computed within the Boltzmann transport theory. We exemplify our approach with n-type Mg3Sb2, a promising thermoelectric material with a challenging large unit cell and low symmetry. Notably, our method attains competitive accuracy, requiring less than 10% of the computational cost compared to state-of-the-art ab initio methods, dropping to 1% for simpler materials. Additionally, our approach provides explicit information on individual scattering processes, offering an alternative that combines efficiency, robustness, and flexibility beyond the commonly employed constant relaxation time approximation with the accuracy of fully first-principles calculations.