We perform molecular dynamics simulation on a glass-forming liquid binarymixture with the soft-core potential in three dimensions. We investigatecrossover of the configuration changes caused by stringlike jump motions. Withlowering the temperature $T$, the motions of the particles composing stringsbecome larger in sizes and displacements, while those of the particlessurrounding strings become smaller. Then, the contribution of the latter totime-correlation functions tends to be long-lived as $T$ is lowered. As aresult, the relaxation time $\tau_\alpha$ and the viscosity $\eta$ grow moresteeply than the inverse diffusion constant $D^{-1}$ at low $T$, leading tobreakdown of the Stokes-Einstein relation. At low $T$, the diffusion occurs asactivation processes and may well be described by short-time analysis of rarejump motions with broken bonds and large displacements. Some characteristicfeatures of the van Hove self-correlation function arise from escape jumps overhigh potential barriers.
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机译：我们在具有软核势的三维玻璃形成液体二元混合物上进行分子动力学模拟。我们研究由弦状跳跃运动引起的配置变化的交叉。随着温度$ T $的降低，组成弦的粒子的运动的尺寸和位移变大，而围绕弦的粒子的运动变小。然后，随着$ T $的降低，后者对时间相关函数的贡献趋于长期存在。结果，弛豫时间$ \ tau_ \ alpha $和粘度$ \ eta $的增长比低T $$时的反扩散常数$ D ^ {-1} $增长得更快，从而导致了Stokes-Einstein关系的破裂。在低的$ T $时，扩散发生在激活过程中，可以通过对具有断裂键和大位移的稀有跳跃运动进行短时分析来描述。范霍夫自相关函数的某些特征是由高势垒上的逃逸跳跃引起的。
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