Solid interfaces with exceptionally low or high thermal conductance are of intense scientific and practical interest. However, realizing such interfaces is challenging due to a lack of knowledge of the phonon transmission coefficients between specific modes on each side of the interface and how the coefficients are affected by atomic scale structure. Here, we report an ab initio based study of phonon transmission at Si/Ge interfaces using a recent extension of the atomistic Green's function method that resolves transmission coefficients by mode. These results provide a detailed framework to investigate the precise transmission and reflection processes that lead to thermal resistance and how they depend on phonon frequency as well as incident angle. We find that the transmission and reflection processes can be partly explained with familiar concepts such as conservation of transverse momentum, but we also find that numerous phonons have zero transmission coefficient despite the existence of modes that satisfy transverse momentum conservation. This work provides detailed insights into precisely which phonons transmit or reflect at interfaces, knowledge necessary to design solid interfaces with extreme values of thermal conductance for thermoelectricity and heat management applications.

中文翻译：

---

使用原子格林函数在Si / Ge接口进行模式解析声子传输的从头开始

具有极低或高导热率的固体界面具有强烈的科学和实践意义。然而，由于缺乏对界面的每一侧上的特定模式之间的声子传输系数以及该系数如何受到原子尺度结构的影响的知识，实现这样的界面是有挑战性的。在这里，我们报告一个从头算基于原子/格林函数方法的最新扩展的基于Si / Ge界面声子传输的研究，该方法可以按模式解析传输系数。这些结果为研究导致热阻的精确透射和反射过程以及它们如何依赖声子频率以及入射角提供了详细的框架。我们发现可以用熟悉的概念（例如，横向动量守恒）部分解释透射和反射过程，但是我们也发现，尽管存在满足横向动量守恒的模态，但许多声子的透射系数为零。这项工作提供了详细的见解，以准确地了解声子在界面上的传输或反射，