Diffusion coefficient calculation of iron in liquid lead using molecular dynamics method with new mixing rule for Lennard-Jones potential parameters

DOI: 10.48129/kjs.17205

Abstract

The diffusion coefficient data of materials are very important for many applications. These can be calculated theoretically up to considerable accuration. Using molecular dynamics simulation we can compute this property for any temperatures. The corrosion phenomena of steels in (fast) nuclear reactor can be related and studied based on the the diffusion process of iron atoms which dissolves into liquid lead coolant. One of the very popular type of interatomic interaction potential of the materials is the Lennard-Jones potential. For the Lennard-Jones interaction type between a pair of different elements we can use the mixing rule of the very popular Lorentz-Bertholet or the Halgren HHG or the Waldman Hagler or any other forms of mixing rules.  However for metal system as the liquid metal corrosion, the above mixing rules maybe not accurate enough. In current work we suggest a new mixing rule for better result of diffusion coefficient calculation. We have computed the diffusion coefficient of iron in liquid lead based our new mixing rule, that D_Fe⇢Pb(T=750 ℃) = 2.719× 10^-9  [m²/s]. This is about 0.40% out of experimental result 2.8 x10^-9 m²/s.