arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1807.03552cond-mat.soft
收藏

原子尺度下Green-Kubo应力关联函数和模型液体中的长程键取向有序

Green-Kubo stress correlation function at the atomic scale and a long-range bond-orientational ordering in a model liquid

V. A. Levashov

摘要:

最近,不同的作者从微观角度对粘度和Green-Kubo应力关联函数进行了一些研究。在大多数这些和早期的作品中,原子水平的应力是应力的最小元素。对于成对相互作用势,也可以考虑与相互作用粒子对相关的应力张量作为应力的最小元。从这个角度来看,原子级应力不是最小应力元,而是所有涉及选定粒子的成对应力元的总和。本文以相互作用对的应力张量为基本应力元,从微观角度考虑Green-Kubo应力关联函数。所得到的结果表明,在所研究的模型液体中存在长程键取向顺序,自然阐明键取向顺序与粘度的连接。结果表明,长程键取向有序性在电子对应力关联函数中的表达比在原子应力关联函数中的表达更清楚。另一方面,以前观察到的应力波更好地表示在原子应力关联函数。我们还解决了我们的方法与以前的键取向顺序的考虑的密切联系。最后,我们考虑在选定的距离的键应力和原子应力相关产品的概率分布。所获得的概率分布的字符提出了问题的平均关联函数在大距离的意义。

英文摘要:

Recently there have been several considerations by different authors of viscosity and the Green-Kubo stress correlation function from the microscopic perspective. In most of these and earlier works the atomic level stress is the minimal element of stress. It is also possible to consider, for pairwise interaction potentials, as the minimal elements of stress, the stress tensors associated with the pairs of interacting particles. From this perspective, the atomic level stress is not the minimal stress element, but a sum of all pair stress elements in which involved a selected particle. In this paper, we consider the Green-Kubo stress correlation function from a microscopic perspective using the stress tensors of interacting pairs as the basic stress elements. The obtained results show the presence of a long-range bond-orientational order in the studied model liquid and naturally elucidate the connection of the bond-orientational order with viscosity. It turns out that the long-range bond-orientational order is more clearly expressed in the pairs' stress correlation function than in the atomic stress correlation function. On the other hand, previously observed stress waves are much better expressed in the atomic stress correlation functions. We also address the close connection of our approach with the previous bond-orientational order considerations. Finally, we consider the probability distributions for the bond-stress and atomic stress correlation products at selected distances. The character of the obtained probability distributions raises questions about the meaning of the average correlation functions at large distances.

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。

↑