Harmonic vibrational excitations in disordered solids and the "boson peak"
Harmonic vibrational excitations in disordered solids and the "boson peak"
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DOI：
10.1103/physrevlett.81.136
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发表时间：
1998-07-06
影响因子：
8.6
通讯作者：
Ganter, C
中科院分区：
文献类型：
--
作者：
Schirmacher, W;Diezemann, G;Ganter, C
本文考虑了简单立方晶格上具有空间涨落最近邻力常数的耦合经典谐振子系统。该模型是解决了数值对角化和应用单键相干势近似。对态密度g（ω）的计算结果彼此吻合得很好.如果系统接近稳定性的边界，则低频峰值出现在量G（ω）/ω（2）中，作为不稳定性的前兆。我们认为，这个峰是类似的“玻色子峰，”观察到的结构玻璃和其他无序固体。通过能级距离统计，我们证明了该峰与局域态无关。
We consider a system of coupled classical harmonic oscillators with spatially fluctuating nearest-neighbor force constants on a simple cubic lattice. The model is solved both by numerical diagonalization and by applying the single-bond coherent potential approximation. The results for the density of states g(omega) an in excellent agreement with each other. if the system is near the borderline of stability a low-frequency peak appears in the quantity g(omega)/omega(2) as a precursor of the instability. We argue that this peak is the analogon of the "boson peak," observed in structural glasses and other disordered solids. By means of the level distance statistics we show that the peak is not associated with localized states.