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，将密度泛函理论、晶格动力学、分子动力学和蒙特卡罗方法无缝地结合在一起，分析了单晶、代位合金和纳米结构块体热电材料中依赖于声子模的热输运。我们以半-Heusler化合物、硫系化合物铅和硅化镁为基础材料。在验证了理论计算与实验结果的基础上，对合金晶体进行了扩展计算，以阐明热导率降低与组成比的关系。此外，通过对累积导热系数和导热系数光谱的计算，我们确定了每种基材合适的纳米结构类别。

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.