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arXiv 1002.0520cond-mat.soft
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动力学交叉处的动力学不均匀性

Kinetic Heterogeneities at Dynamical Crossovers

T. K. Haxton, A. J. Liu

摘要:

我们进行分子动力学模拟的模型玻璃形成液体来测量动力学不均匀性的大小,使用动态磁化率$χ_{\rm ss}(a, t)$,量化的粒子的数量,其动态相关的长度尺度$a$和时间尺度$t$。通过测量作为$a$和$t$两者的函数的$χ_{\rm ss}(a, t)$,我们在距离$a^\star$和时间$t^\star$处定位局部最大值$χ^\star$。附近的动态玻璃化转变,我们发现两种类型的最大值,都与交叉的动力学行为:一个较小的最大值对应的交叉从弹道到子扩散运动,和一个较大的最大值对应的交叉从子扩散到扩散运动。我们的研究结果表明,动力学的不均匀性不一定是一个即将到来的玻璃或堵塞过渡的签名。

英文摘要:

We perform molecular dynamics simulations of a model glass-forming liquid to measure the size of kinetic heterogeneities, using a dynamic susceptibility $χ_{\rm ss}(a, t)$ that quantifies the number of particles whose dynamics are correlated on the length scale $a$ and time scale $t$. By measuring $χ_{\rm ss}(a, t)$ as a function of both $a$ and $t$, we locate local maxima $χ^\star$ at distances $a^\star$ and times $t^\star$. Near the dynamical glass transition, we find two types of maxima, both correlated with crossovers in the dynamical behavior: a smaller maximum corresponding to the crossover from ballistic to sub-diffusive motion, and a larger maximum corresponding to the crossover from sub-diffusive to diffusive motion. Our results indicate that kinetic heterogeneities are not necessarily signatures of an impending glass or jamming transition.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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