Direct evaluation of the physical characteristics of Yukawa fluids based on a simple approximation for the radial distribution function

I.I Fairushin,S.A Khrapak,A.V Mokshin

doi:10.1016/j.rinp.2020.103359

I.I Fairushin, S.A Khrapak + Show 1 more

Open Access

https://doi.org/10.1016/j.rinp.2020.103359

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Abstract

We propose a simple analytical approximation for the radial distribution function (RDF) in a single-component Yukawa fluid. The proposed RDF depends on the two input parameters – the non-ideality parameter Γ and the structure (screening) parameter κ, which determine the thermodynamic state of Yukawa systems. We demonstrate that various physical properties can be directly calculated using the proposed RDF. In particular, the internal energy and pressure, the excess entropy in the pair approximation, and the dispersion relation of longitudinal acoustic-like collective excitations are calculated. These theoretical results are compared with the results from molecular dynamics simulations and good overall agreement is observed in the investigated regime of screening and coupling parameters.

Highlights

(x) is the Heaviside stepfunction and xeff is the effective correlational hole radius, which can be determined by requiring that the internal energy or pressure are correctly evaluated from the approximation (7)
The simplest form (7) does not account for the most prominent signature of the liquid state, which is manifested in the characteristic maximum of the radial distribution function (RDF)
The results of numerical calculations for the reduced excess internal energy Uex, reduced excess internal pressure Pex and reduced pair excess entropy Sex2, obtained using the approximation (8) along with those obtained using the actual RDFs from MD simulations are presented in

Summary

Introduction

Can be used within the framework of the quasilocalized charge approximation (QLCA) [10,7,11,12,13] to obtain simple analytical expressions for the dispersion of longitudinal and transverse collective excitations in Yukawa fluids. Using this approximation we calculate the internal energy, pressure, the pair excess entropy, and the dispersion relation of the longitudinal collective mode.

Results

Conclusion