npj Computational Materials

Accelerating evaluation of converged lattice thermal conductivity (对收敛点阵热导率的快速测定)
Guangzhao Qin & Ming Hu
npj Computational Materials 4:3 (2018)
doi:10.1038/s41524-017-0058-3
Published online:17 January 2018
Abstract| Full Text | PDF OPEN

摘要:高通量计算材料设计是材料科学中的一个新兴领域，该领域的基础是对材料物理性质的快速评估。晶格热导率是材料的重要属性，有着广泛用途。然而，由于计算过程十分耗时费钱，热导率的高通量计算仍是一个挑战。本研究提出了一个简明的策略来有效地加速计算过程，以获得准确的、收敛的热导率。该策略基于声子玻尔兹曼输运方程和第一性原理计算框架建立，基于对原子间二阶力常数（harmonic interatomic force constants, IFCs）的分析，可以直接确定收敛的截断半径（其为计算非谐力常数的关键参数，r^cutoff），由此可得到合理的计算结果。此外，我们还找到了一个简单的方法可以大大提高计算速度（〜10倍），即基于热导率随截断半径的收敛关系来快速获得非谐力常数，最终确认所选择的截断半径是否合适。为了验证该方法的有效性，以二维石墨烯、磷烯以及SnSe块体为对象，研究了长期存在争论的低维系统热导发散问题。本研究中提出的量化策略可以作为一种快速可靠的测定热导率的候选方法，从而为高通量材料的筛选和热输运性能的设计提供有用的工具。　　

Abstract:High-throughput computational materials design is an emerging area in materials science, which is based on the fast evaluation of physical-related properties. The lattice thermal conductivity (κ) is a key property of materials for enormous implications. However, the high-throughput evaluation of κ remains a challenge due to the large resources costs and time-consuming procedures. In this paper, we propose a concise strategy to efficiently accelerate the evaluation process of obtaining accurate and converged κ. The strategy is in the framework of phonon Boltzmann transport equation (BTE) coupled with first-principles calculations. Based on the analysis of harmonic interatomic force constants (IFCs), the large enough cutoff radius (rcutoff), a critical parameter involved in calculating the anharmonic IFCs, can be directly determined to get satisfactory results. Moreover, we find a simple way to largely (~10 times) accelerate the computations by fast reconstructing the anharmonic IFCs in the convergence test of κ with respect to the rcutof, which finally confirms the chosen rcutoff is appropriate. Two-dimensional graphene and phosphorene along with bulk SnSe are presented to validate our approach, and the long-debate divergence problem of thermal conductivity in low-dimensional systems is studied. The quantitative strategy proposed herein can be a good candidate for fast evaluating the reliable κ and thus provides useful tool for high-throughput materials screening and design with targeted thermal transport properties.

Editorial Summary

THERMOELECTRICS: Speeding up the calculations (热电材料：加快计算速度)

按本研究报道，将声子玻尔兹曼输运方程与第一性原理计算相结合可以显著加速很多材料的晶格热导率的计算。晶格热导率是决定材料热电转换性能的重要参数。然而，其计算量通常很大，是热电材料的高通量计算筛选的瓶颈之一。热导率的计算方法大多依赖于原子间力常数的计算；现在，来自德国亚琛的Guangzhao Qin 和Ming Hu提出了一种新方法，可将相关计算速度提升约10倍。该方法主要基于截断距离的获得和有效计算区间的确定。他们这一方法已被用于石墨烯等材料的热导率计算，并可用于材料热导率的高通量计算中。

A combination of phonon Boltzmann transport equation with first-principles calculations can significantly speed up the calculation of the lattice thermal conductivity for a number of materials. The lattice thermal conductivity is a parameter that is crucial for determining the energy conversion efficiency of thermoelectric materials. However, its evaluation is based on time-consuming calculations, which limits the possibility to exploit high-throughput computations for determining high-performance thermoelectric materials. Most approaches rely on the calculation of interatomic force constants; now, Guangzhao Qin and Ming Hu from Aachen, Germany, propose a way to speed up these calculations by almost an order of magnitude, by solving the cutoff distance problem and determining the necessary region for calculations. The proposed methodology is used to determine the lattice conductivity of graphene and other materials, and will be useful for the investigation of thermal properties of various materials through high-throughput studies.