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arXiv 0908.3014cond-mat.softcond-mat.mtrl-sci
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高斯核混合物结构和动力学的成分和浓度异常

Composition and concentration anomalies for structure and dynamics of Gaussian-core mixtures

Mark J. Pond, William P. Krekelberg, Vincent K. Shen, Jeffrey R. Errington, Thomas M. Truskett

摘要:

我们报告的分子动力学模拟结果的两种组分的流体混合物的高斯核心颗粒,重点是示踪剂的扩散系数和静态对相关性如何依赖于温度,颗粒浓度和组合物。在低粒子浓度下,这些系统表现得像简单的原子混合物。然而,对于中间浓度,两种物质的单粒子动力学在很大程度上解耦,引起以下异常趋势。增加流体的浓度(在固定的组成下)或较大颗粒的摩尔分数(在固定的颗粒浓度下)增强较大颗粒的示踪剂扩散率,但减小较小颗粒的示踪剂扩散率。事实上,在足够高的颗粒浓度下,较大的颗粒比较小的颗粒表现出更高的迁移率。这些动态行为中的每一个都伴随着相应的结构趋势,其特征在于浓度或成分如何影响静态对相关性的强度。具体而言,这里观察到的动态趋势是一致的,与一个单一的经验标度律,涉及一个适当的归一化示踪剂的扩散率,其对相关贡献的过剩熵。

英文摘要:

We report molecular dynamics simulation results for two-component fluid mixtures of Gaussian-core particles, focusing on how tracer diffusivities and static pair correlations depend on temperature, particle concentration, and composition. At low particle concentrations, these systems behave like simple atomic mixtures. However, for intermediate concentrations, the single-particle dynamics of the two species largely decouple, giving rise to the following anomalous trends. Increasing either the concentration of the fluid (at fixed composition) or the mole fraction of the larger particles (at fixed particle concentration) enhances the tracer diffusivity of the larger particles, but decreases that of the smaller particles. In fact, at sufficiently high particle concentrations, the larger particles exhibit higher mobility than the smaller particles. Each of these dynamic behaviors is accompanied by a corresponding structural trend that characterizes how either concentration or composition affects the strength of the static pair correlations. Specifically, the dynamic trends observed here are consistent with a single empirical scaling law that relates an appropriately normalized tracer diffusivity to its pair-correlation contribution to the excess entropy.

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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