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arXiv 1603.06259cond-mat.dis-nncond-mat.soft
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强玻璃形成剂SiO $_2$老化的普适标度

Universal Scaling in the Aging of the Strong Glass Former SiO$_2$

Katharina Vollmayr-Lee, Christopher H. Gorman, Horacio E. Castillo

摘要:

我们发现,一个强大的玻璃前体的老化动力学显示出一个惊人的简单的标度行为,连接的平均动态与其波动,即动力学的不均匀性。我们进行分子动力学模拟的SiO $_2$与BKS相互作用,淬火系统从高到低的温度,并研究系统的演变作为一个功能的等待时间$t_{\rm w}$测量的瞬间淬火。我们发现动态极化率$χ_4$的老化行为和局域非相干中间散射函数$f_{{\rm s},{\mathbf r}}$的概率分布$P(f_{{\rm s},{\mathbf r}})$的老化行为都可以用全局非相干中间散射函数$C$的简单标度形式来描述。已经发现的描述几种易碎玻璃成型体老化的标度形式是相同的,并且在$P(f_{{\rm s},{\mathbf r}})$的情况下,也已经在理论上预测了标度形式。对所涉及的长度尺度的深入研究突出了中间长度尺度的重要性。我们还直接分析了慢老化动力学的标度与粒子类型和波矢$q$的关系,发现慢老化动力学的平均值和涨落都受一个独特的老化钟控制,该钟不仅与波矢$q$无关,而且对O和Si原子也是一样的.

英文摘要:

We show that the aging dynamics of a strong glass former displays a strikingly simple scaling behavior, connecting the average dynamics with its fluctuations, namely the dynamical heterogeneities. We perform molecular dynamics simulations of SiO$_2$ with BKS interactions, quenching the system from high to low temperature, and study the evolution of the system as a function of the waiting time $t_{\rm w}$ measured from the instant of the quench. We find that both the aging behavior of the dynamic susceptibility $χ_4$ and the aging behavior of the probability distribution $P(f_{{\rm s},{\mathbf r}})$ of the local incoherent intermediate scattering function $f_{{\rm s},{\mathbf r}}$ can be described by simple scaling forms in terms of the global incoherent intermediate scattering function $C$. The scaling forms are the same that have been found to describe the aging of several fragile glass formers and that, in the case of $P(f_{{\rm s},{\mathbf r}})$, have been also predicted theoretically. A thorough study of the length scales involved highlights the importance of intermediate length scales. We also analyze directly the scaling dependence on particle type and on wavevector $q$, and find that both the average and the fluctuations of the slow aging dynamics are controlled by a unique aging clock, which is not only independent of the wavevector $q$, but is the same for O and Si atoms.

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