Origins of the two-step relaxation and the boson peak in an alkali silicate glass studied by molecular-dynamics simulation.
Origins of the two-step relaxation and the boson peak in an alkali silicate glass studied by molecular-dynamics simulation.
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DOI：
10.1103/physreve.52.2681
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发表时间：
1995-09
期刊：
影响因子：
--
通讯作者：
Habasaki;Okada;Hiwatari
中科院分区：
文献类型：
--
作者：
Habasaki;Okada;Hiwatari
本文对偏硅酸锂（li2sio3）进行了分子动力学模拟。在700 K时，在Li离子的密度相关函数（自部分）中观察到一个明显的两步弛豫。在函数的第二（β弛豫）区域发现振荡，这归因于所谓的“玻色子峰”。“O和Si的振荡比Li的更明显。最慢弛豫（α弛豫）可以很好地拟合为拉伸指数形式，并证实了这种衰减的起源是跳跃运动的等待时间分布。发现β弛豫和玻色子峰都是由相关运动引起的。
A molecular-dynamics simulation of lithium metasilicate (Li 2 SiO 3) has been performed. A clear two-step relaxation was observed at 700 K in a density correlation function (self-part) for Li ions following an exponential decay by vibrational motion. Oscillation is found in the second (β relaxation) region of the function, which is attributed to the so-called ‘‘boson peak.’’The oscillation is clearer for O and Si than for Li. T he slowest relaxation (α relaxation) can be well fitted to a stretched exponential form, and an origin of this type of decay is confirmed to be a waiting time distribution of jump motions. Both the β relaxation and the boson peak are found to be due to correlated motion.