Enskog Theory Of Self-diffusion Of Liquid Metal Atoms

The study of liquid metal microdynamics plays an important role in understanding the transport behavior of liquid metal.In this paper,the self-diffusion behavior of liquid metal atoms is studied using the modified Enskog theory of hard spheres and molecular dynamics simulations,and the fitness of the modified Enskog theory is evaluated.The main content of this article includes the following two points.First of all,the hard sphere model is the simplest solvable model in Enskog’s theory.In practice,the liquid metal atom is the closest to this model.In this paper,we have considered the deviation the metal atom from the hard sphere model.Namely,as the temperature increases,the collision depth between liquid metal atoms increases,and its effective diameter will decrease accordingly.The relationship between the effective diameter of the hard sphere model and the temperature is derived.Thus,the Enskog hard sphere theory is revised,and a formula for calculating the self-diffusion coefficient of liquid metal atoms is obtained more accurately.Secondly,the molecular dynamics software LAMMPS was used to simulate the atomic self-diffusion of liquid metals of aluminum,magnesium and iron.The self-diffusion coefficients of these metal atoms obtained by the simulations are compared with the calculation results of the modified Enskog theory.The following conclusions are drawn:(1)The modified Enskog theory is more suitable for liquid metals with high hardness;(2)In the Enskog modified theory,the correction of the self-diffusion coefficient comes from two parts,the change in the effective diameter and the change in the density of fluids.The change of the density of fluid contribute the major part to the self-diffusion coefficient of liquid metal atoms.