Random-walk shielding-potential viscosity model for warm dense metals

TL;DR

The paper introduces the RWSP-VM, a new model that accurately predicts the viscosity of warm dense metals by incorporating ion random walks and Debye shielding, validated against molecular dynamics simulations.

Contribution

A novel analytical viscosity model for warm dense metals that integrates ion random-walk statistics and shielding effects, validated against MD simulations and existing models.

Findings

RWSP-VM agrees well with MD simulation data.

The model is consistent with plasma and Yukawa viscosity models.

RWSP-VM is efficient and broadly applicable.

Abstract

We develop a novel model, called the ``random-walk shielding-potential viscosity model'' (RWSP-VM) that introduces the statistics of random-walk ions and the Debye shielding effect to describe the viscosities of warm dense metals. The viscosities of several metals with low to high atomic number (Be, Al, Fe, and U) are calculated using the analytical expression of RWSP-VM. Additionally, we simulate the viscosities of Fe and Be by employing the Langevin molecular dynamics (MD) and classical MD, while the MD data for Al and U are obtained from a previous work. The results of the RWSP-VM are in good agreement with the MD results, which validates the proposed model. Furthermore, we compare the RWSP-VM with the one-component plasma model and Yukawa viscosity model and show that the three models yield results in excellent agreement with each other in the regime where the RWSP-VM is applicable. These results indicate that the RWSP-VM is a universal, accurate, and highly efficient model for calculating the viscosity of metals in the warm dense state. The code of the proposed RWSP-VM is provided, and it is envisaged that it will have broad application prospects in numerous fields.