Spontaneous and induced dynamic fluctuations in glass formers. I. General results and dependence on ensemble and dynamics
Spontaneous and induced dynamic fluctuations in glass formers. I. General results and dependence on ensemble and dynamics
复制标题
DOI：
10.1063/1.2721554
复制
发表时间：
2007-05-14
影响因子：
4.4
通讯作者：
Reichman, D. R.
中科院分区：
文献类型：
--
作者：
Berthier, L.;Biroli, G.;Reichman, D. R.
我们从理论上和数值上研究了一组多点动态磁化率，量化了玻璃成形材料中动态非均质性的强度和特征长度尺度。我们使用一般的理论论据（涨落-耗散关系和相关动力场理论的对称性）来将平均双时间相关器对温度和密度的敏感性与局部动力学的自发涨落联系起来。然后将我们的理论结果与两种具有代表性的玻璃形成液体的牛顿、布朗和蒙特卡罗动力学的分子动力学模拟进行比较，一种是脆弱的二元Lennard-Jones混合物，一种是强玻璃形成物二氧化硅模型。我们详细论证了Berthier [Science 310, 1797(2005)]提出的主张，即相关函数的温度依赖性允许人们在玻璃系统的动态长度尺度上提取有用的信息。我们还讨论了通过守恒量选择微观动力学和统计系综相关的一些微妙问题，发现守恒量在确定动态相关性方面起着重要作用。(C) 2007年美国物理研究所。
We study theoretically and numerically a family of multipoint dynamic susceptibilities that quantify the strength and characteristic length scales of dynamic heterogeneities in glass-forming materials. We use general theoretical arguments (fluctuation-dissipation relations and symmetries of relevant dynamical field theories) to relate the sensitivity of averaged two-time correlators to temperature and density to spontaneous fluctuations of the local dynamics. Our theoretical results are then compared to molecular dynamics simulations of the Newtonian, Brownian, and Monte Carlo dynamics of two representative glass-forming liquids, a fragile binary Lennard-Jones mixture, and a model for the strong glass-former silica. We justify in detail the claim made by Berthier [Science 310, 1797 (2005)] that the temperature dependence of correlation functions allows one to extract useful information on dynamic length scales in glassy systems. We also discuss some subtle issues associated with the choice of microscopic dynamics and of statistical ensemble through conserved quantities, which are found to play an important role in determining dynamic correlations. (C) 2007 American Institute of Physics.