Theoretical design of thermal condutive- and thermoelectric- devices by all electron mixed basis ab initio calculatio

由于热现象是一个复杂的问题，不能用标准的从头算能量估计来处理，只能发展和应用唯象模型。 因此，人们认为，没有实验的帮助，就不可能从理论上估计导热系数，从而设计出性能更好的热电器件。 本研究试图从基本量子力学出发，定量地估算导热系数和热电转换效率。 我们将估计谐振晶格振动的方法扩展到非谐振振动，并使用计算的声子、估计的热导率和热电转换率。 首先，我们估计BiTe，这是已知的实验，并证实了我们的方法的准确性。 在此确认之后，我们试图估计GeSe的热性质以设计新的有用材料。

Since thermal phenomena are complex problem which can not be treated within the standard ab initio energy estimation, and only phenomenological models had been developed and applied. Therefore, it was believed to be impossible to estimate theoretically thermal conductivity without experimental help, and design better performance thermoelectric device. The present research tries to start from thebasic quantum mechanics and to estimate thermal conductivity and thermoelectric coversion efficiency quantatatively. We have extended our method of estimating harmonic lattice vibration to unharmonic vibration, and using the computed phonons, estimated thermal conductivity and thermoelectric conversion rate. Firstly we estimated for BiTe, which is known experimentally, and confirmed the accuracy of our method. After this confirmation, we have tried to estimate thermal properties in GeSe to design new useful materials.