Yang J, Wang Yun-Jiang, Ma E, Zaccone A, Dai L H, Jiang M Q
State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
School of Engineering Science, University of Chinese Academy of Sciences, Beijing 101408, People's Republic of China.
Phys Rev Lett. 2019 Jan 11;122(1):015501. doi: 10.1103/PhysRevLett.122.015501.
It has so far remained a major challenge to quantitatively predict the boson peak, a THz vibrational anomaly universal for glasses, from features in the amorphous structure. Using molecular dynamics simulations of a model Cu_{50}Zr_{50} glass, we decompose the boson peak to contributions from atoms residing in different types of Voronoi polyhedra. We then introduce a microscopic structural parameter to depict the "orientational order," using the vector pointing from the center atom to the farthest vertex of its Voronoi coordination polyhedron. This order parameter represents the most probable direction of transverse vibration at low frequencies. Its magnitude scales linearly with the boson peak intensity, and its spatial distribution accounts for the quasilocalized modes. This correlation is shown to be universal for different types of glasses.
到目前为止，从非晶结构的特征定量预测玻色子峰（一种玻璃普遍存在的太赫兹振动异常）仍然是一项重大挑战。通过对模型Cu₅₀Zr₅₀玻璃进行分子动力学模拟，我们将玻色子峰分解为位于不同类型沃罗诺伊多面体中的原子的贡献。然后，我们引入一个微观结构参数来描述“取向有序性”，使用从中心原子指向其沃罗诺伊配位多面体最远顶点的向量。这个有序参数代表了低频下横向振动的最可能方向。其大小与玻色子峰强度呈线性比例关系，其空间分布解释了准局域模式。这种相关性被证明对不同类型的玻璃是普遍存在的。
