Self-diffusion in single-component Yukawa fluids

Sergey Khrapak,Boris Klumov,Lenaic Couedel

doi:10.1088/2399-6528/aaba23

Abstract

It was suggested in the literature that the self-diffusion coefficient of simple fluids can be approximated as a ratio of the squared thermal velocity of the atoms to the ‘fluid Einstein frequency,’ which can thus serve as a rough estimate of the friction (momentum transfer) rate in the dense fluid phase. In this article we test this suggestion using a single-component Yukawa fluid as a reference system. The available simulation data on self-diffusion in Yukawa fluids, complemented with new data for Yukawa melts (Yukawa fluids near the freezing phase transition), are carefully analyzed. It is shown that although not exact, this earlier suggestion nevertheless provides a very sensible way of normalization of the self-diffusion constant. Additionally, we demonstrate that certain quantitative properties of self-diffusion in Yukawa melts are also shared by systems like one-component plasma and liquid metals at freezing, providing support to an emerging dynamical freezing indicator for simple soft matter systems. The obtained results are also briefly discussed in the context of the theory of momentum transfer in complex (dusty) plasmas.

Highlights

De Gennes in his seminal paper on liquid dynamics and inelastic scattering of neutrons [1] related the selfdiffusion coefficient in classical atomic liquids to liquid structure, measured in terms of the radial distribution function (RDF) g(r), and the potential of inter-atomic interactions f(r)
In this article we demonstrate this by a detailed investigation of the behavior of DE in one-component Yukawa fluids
In this paper we use the data for the self-diffusion coefficient in Yukawa fluids tabulated by Ohta and Hamaguchi in a wide range of κ and Γ values corresponding to the fluid state [32]

Summary

Introduction

De Gennes in his seminal paper on liquid dynamics and inelastic scattering of neutrons [1] related the selfdiffusion coefficient in classical atomic liquids to liquid structure, measured in terms of the radial distribution function (RDF) g(r), and the potential of inter-atomic interactions f(r). The relation he put forward is D= p 2 v 2 T WE (1). Where vT = T m is the thermal velocity, T is the temperature, m is the atomic mass, and the characteristic frequency ΩE is defined as ò WE2 = n 3m ¥ drg (r)Df (r), (2)

Methods

Results

Conclusion