非晶态固体振动频率的随机诱导重分布
Randomness-Induced Redistribution of Vibrational Frequencies in Amorphous Solids
摘要：
多年来，文献中对非晶态固体态密度低频部分的讨论主要是通过将测量或模拟的态密度与经典德拜模型进行比较。由于这个模型很难适用于手头的材料，这就造成了一些关于所谓的“玻色子峰”的存在和普遍性的混乱，而玻色子峰是由这种比较产生的。我们建议人们应该注意不同方面的无序所起的不同作用，第一个是相互作用强度的无序，第二个是位置无序，第三个是协调无序。这些对态密度的低频部分有不同的影响。我们研究了一些易处理的模型在一维和二维的状态密度，并达到一个更清晰的画面，软化和重新分配的频率在这样的材料。讨论了无序度对弹性模量的影响以及弹性模量与频率软化的关系，得出了玻色子峰并不普适的结论。
英文摘要：
Much of the discussion in the literature of the low frequency part of the density of states of amorphous solids was dominated for years by comparing measured or simulated density of states to the classical Debye model. Since this model is hardly appropriate for the materials at hand, this created some amount of confusion regarding the existence and universality of the so- called ``Boson Peak'' which results from such comparisons. We propose that one should pay attention to the different roles played by different aspects of disorder, the first being disorder in the interaction strengths, the second positional disorder, and the third coordination disorder. These have different effects on the low-frequency part of the density of states. We examine the density of states of a number of tractable models in one and two dimensions, and reach a clearer picture of the softening and redistribution of frequencies in such materials. We discuss the effects of disorder on the elastic moduli and the relation of the latter to frequency softening, reaching the final conclusion that the Boson peak is not universal at all.
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