Echoes from anharmonic normal modes in model glasses
Echoes from anharmonic normal modes in model glasses
复制标题
模型眼镜中非谐波简正模的回波
DOI：
10.1103/physreve.93.032905
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发表时间：
2016
影响因子：
2.4
通讯作者：
Nagel, Sidney R.
中科院分区：
文献类型：
--
作者：
Burton, Justin C.;Nagel, Sidney R.
玻璃在温度K下表现出广泛的非线性声学现象。这种行为传统上被解释为弱耦合的二能级隧穿态的系综，该理论也用于描述低温下玻璃的热力学性质。在这一领域中，最引人注目的声学特征之一是声子回波的存在，这一特征与NMR中具有相同形式的自旋回波的两能级系统有关。在这里，我们报告存在一个明显不同类型的声学回声在经典模型的玻璃材料。我们的模拟包括有限范围的，排斥球和粒子的吸引力使用Lennard-Jones相互作用。我们表明，这些回声是由于非谐，弱耦合的振动模式，并可能提供一个替代的解释在玻璃中观察到的声子回声在低温下。
Glasses display a wide array of nonlinear acoustic phenomena at temperaturesK. This behavior has traditionally been explained by an ensemble of weakly coupled, two-level tunneling states, a theory that is also used to describe the thermodynamic properties of glasses at low temperatures. One of the most striking acoustic signatures in this regime is the existence of phonon echoes, a feature that has been associated with two-level systems with the same formalism as spin echoes in NMR. Here we report the existence of a distinctly different type of acoustic echo in classical models of glassy materials. Our simulations consist of finite-ranged, repulsive spheres and also particles with attractive forces using Lennard-Jones interactions. We show that these echoes are due to anharmonic, weakly coupled vibrational modes and perhaps provide an alternative explanation for the phonon echoes observed in glasses at low temperatures.