Improving bulk thermoelectric materials using heat conduction calculations based on first principles

我们开发了一个多尺度声子输运计算工具，无缝地结合密度泛函理论，晶格动力学，分子动力学，和蒙特-卡罗方法来分析声子模式相关的热输运在单晶，替代合金，和纳米结构的大块热电材料。我们有针对性的半赫斯勒化合物，铅硫族化物，镁硅化物作为基础材料。在与实验进行比较验证的计算后，扩展的计算进行合金晶体，以澄清的热导率降低的组成比的依赖性。此外，通过计算的累积热导率和热导率谱，我们已经确定了适当的类的纳米结构的每种基础材料。

We developed a multiscale phonon transport calculation tool by seamlessly combining density functional theory, lattice dynamics, molecular dynamics, and Monte-Carlo methods to analyze phonon-mode dependent thermal transport in single crystal, substitutional alloy, and nanostructured bulk thermoelectric materials. We have targeted half-Heusler compounds, lead chalcogenides, and magnesium silicide as the base materials. After validating the calculation in comparison with experiments, extended calculations were performed for alloyed crystals to clarify the dependence of the thermal conductivity reduction on the composition ratio. Furthermore, through calculations of cumulative thermal conductivity and thermal conductivity spectra, we have identified the appropriate class of nanostructure for each base materials.