玻璃前躯体动力学异质性空间分布及其演化的二维分子动力学模拟研究
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摘要
玻璃具有晶体的力学刚性,但是其粒子排布并不具有晶体的长程有序,而是类似于液体的粒子无规分布[1]。这种无规结构导致随着粒子所处环境的不同,不同粒子表现出不一样的松弛行为[2,3],即,无规结构致使动力学异质性[4-8]。在本工作中,采用二维分子动力学模拟方法[9-11],我们系统研究了玻璃前驱体系中粒子松弛时间的空间分布,并跟踪测量了这种分布随时间的演化过程。研究结果表明:(1)高温条件下,粒子松弛时间的空间分布也存在着一定的差异,但是其演化很快,即,在很短的时间内(t<Glassy materials possess a mechanical rigidity,which is comparable to that of a crystalline material.While mechanically rigid-glasses do not appear to be characterized by any type of longrange order,they resemble ordinary dense liquids.It is natural to think that the presence of structural disorder implies that particles in different environments move differently,i.e.,the structure should be responsible for dynamic heterogeneity.In this work,using molecular dynamics simulation of two-dimensional glass-forming liquids(Kob-Andersen Model with number density 1.15),we systemically investigate the space distributions of relaxation time and follow to measure the evolution of these distributions.Our results show that,at high temperature,the space distribution of relaxation time emerges the heterogeneous behavior,but its evolution reveals no relationship between these distributions of different time even in short time window(t<
引文
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