Probing the validity of the diffuse mismatch model for phonons using atomistic simulations
Probing the validity of the diffuse mismatch model for phonons using atomistic simulations
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DOI：
10.1103/physrevb.95.125434
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发表时间：
2017-03-27
影响因子：
3.7
通讯作者：
Feser, Joseph P.
中科院分区：
文献类型：
--
作者：
Kakodkar, Rohit R.;Feser, Joseph P.
由于其简单的扩散失配模型（DMM）仍然是一个流行的描述声子传输通过固-固边界。然而，目前还不清楚在哪些情况下，DMM应该被期望成为基础物理的有效模型。在这里，它的有效性进行了调查模式的模式，使用三维扩展的频域，完全匹配层（FD-PML）方法，研究面心立方固体与相互扩散原子之间的界面。虽然亚单层水平的相互扩散被发现增加了可用的传输模式的数量，与DMM定性一致，我们没有发现定量或定性的收敛向DMM在更高水平的相互扩散。特别是，相反的DMM的基本假设，模式没有发现失去其初始偏振和波矢量的记忆。随机互扩散和光滑梯度界面的透射系数进行了比较。虽然平滑渐变界面显示出很强的热传导特性，但选择规则仍然禁止许多模式的传输，而相互扩散界面不受这些规则的约束，并且通过以较低的概率传输但使用更宽范围的模式来实现类似的热界面传导。
Due to its simplicity the diffuse mismatch model (DMM) remains a popular description of phonon transmission across solid-solid boundaries. However, it remains unclear in which situations the DMM should be expected to be a valid model of the underlying physics. Here its validity is investigated mode-by-mode using a three-dimensional extension of the frequency domain, perfectly matched layer (FD-PML) method, to study the interface between face-centered cubic solids with interdiffused atoms. While submonolayer levels of interdiffusion are found to increase the number of available modes for transmission, consistent qualitatively with the DMM, we do not find quantitative or qualitative convergence toward the DMM at higher levels of interdiffusion. In particular, contrary to the fundamental assumption of the DMM, modes are not found to lose memory of their initial polarization and wave vector. The transmission coefficients of randomly interdiffused and smoothly graded interfaces are also compared. While smoothly graded interfaces show strong antireflection properties, selection rules still prohibit transmission of many modes, whereas interdiffused interfaces are not subject to such rules and achieve similar thermal interface conductance by transmitting with lower probability but using a wider range of modes.