不那么简单流体中示踪剂扩散系数的广义Rosenfeld标度：混合物和软粒子
Generalized Rosenfeld scalings for tracer diffusivities in not-so-simple fluids: Mixtures and soft particles
摘要：
Rosenfeld [Phys. Rev. A 15，2545（1977）]注意到，将简单单原子平衡流体的输运系数转换为特定的无量纲形式，使它们近似为过剩熵的单值函数。这具有预测价值，因为虽然稠密流体的输运系数很难从第一原理估计，但过剩熵通常可以从液态理论准确预测。在这里，我们使用分子模拟研究罗森菲尔德的观察是否是一个特殊的情况下，一个更一般的比例关系的流动性的混合物中的粒子的过剩熵。具体来说，我们研究示踪剂扩散系数，静态结构，和热力学性质的各种单组分和双组分模型流体系统的硬球或高斯核形式的添加剂或非添加剂的相互作用。模拟的结果表明，混合物的浓度和组合物，颗粒大小的不对称性和添加剂，以及在这些流体中的颗粒间相互作用的强度的影响是一致的经验标度定律有关的过剩熵的一个新的无量纲（广义罗森菲尔德）形式的示踪剂扩散率，我们在这里介绍。示踪剂扩散系数的无量纲形式来自于分子间势和稀释极限中流体的运输/热力学行为的知识。广义Rosenfeld标度需要更少的信息，并提供更准确的预测，无论是Enskog理论或标度的基础上对相关的贡献过剩熵。然而，正如我们所展示的，它也受到一些限制，特别是对于表现出显着解耦的单个组件示踪剂扩散率的系统。
英文摘要：
Rosenfeld [Phys. Rev. A 15, 2545 (1977)] noticed that casting transport coefficients of simple monatomic, equilibrium fluids in specific dimensionless forms makes them approximately single-valued functions of excess entropy. This has predictive value because, while the transport coefficients of dense fluids are difficult to estimate from first principles, excess entropy can often be accurately predicted from liquid-state theory. Here, we use molecular simulations to investigate whether Rosenfeld's observation is a special case of a more general scaling law relating mobility of particles in mixtures to excess entropy. Specifically, we study tracer diffusivities, static structure, and thermodynamic properties of a variety of one- and two-component model fluid systems with either additive or non-additive interactions of the hard-sphere or Gaussian-core form. The results of the simulations demonstrate that the effects of mixture concentration and composition, particle-size asymmetry and additivity, and strength of the interparticle interactions in these fluids are consistent with an empirical scaling law relating the excess entropy to a new dimensionless (generalized Rosenfeld) form of tracer diffusivity, which we introduce here. The dimensionless form of the tracer diffusivity follows from knowledge of the intermolecular potential and the transport / thermodynamic behavior of fluids in the dilute limit. The generalized Rosenfeld scaling requires less information, and provides more accurate predictions, than either Enskog theory or scalings based on the pair-correlation contribution to the excess entropy. As we show, however, it also suffers from some limitations, especially for systems that exhibit significant decoupling of individual component tracer diffusivities.
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