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arXiv 1407.4598cond-mat.mes-hallcond-mat.mtrl-sci
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有效声子谱的布里渊区展开方法

Brillouin zone unfolding method for effective phonon spectra

Timothy B. Boykin, Arvind Ajoy, Hesameddin Ilatikhameneh, Michael Povolotskyi, Gerhard Klimeck

摘要:

热性质在现代电子器件和纳米结构中具有重要意义。当设备由纯材料制成时,计算这些属性是简单的,但当使用合金时就会出现问题。具体来说,只有近似能带结构可以计算随机合金和最常见的虚拟晶体近似(VCA)使用。展开方法[T. B. Boykin,N.哈尔切湾Klimeck和M. Korkusinski,J. Phys.:康登斯马太福音19,036203(2007).]已被证明是非常有用的紧束缚计算的合金电子结构,没有在VCA的问题,和紧束缚和价力场方法之间的声子问题的数学类比表明,他们在这里也被采用。然而,这两个问题的物理性质存在一些差异,需要对电子结构方法进行修改。因此,我们推导出一个声子合金能带结构(振动模式)的方法,我们的紧束缚电子结构方法的基础上,修改带测定方法,以适应不同的物理情况。利用这种方法,我们研究了In $_x$ Ga $_{1-x}$ As合金,发现与现有的实验结果非常吻合。

英文摘要:

Thermal properties are of great interest in modern electronic devices and nanostructures. Calculating these properties is straightforward when the device is made from a pure material, but problems arise when alloys are used. Specifically, only approximate bandstructures can be computed for random alloys and most often the Virtual Crystal Approximation (VCA) is used. Unfolding methods [T. B. Boykin, N. Kharche, G. Klimeck, and M. Korkusinski, J. Phys.: Condens. Matt. 19, 036203 (2007).] have proven very useful for tight-binding calculations of alloy electronic structure without the problems in the VCA, and the mathematical analogy between tight-binding and valence-force-field approaches to the phonon problem suggest they be employed here as well. However, there are some differences in the physics of the two problems requiring modifications to the electronic structure approach. We therefore derive a phonon alloy bandstructure (vibrational mode) approach based on our tight-binding electronic structure method, modifying the band-determination method to accommodate the different physical situation. Using the method, we study In$_x$Ga$_{1-x}$As alloys and find very good agreement with available experiments.

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