Analysis of the Applicability of the Yukawa Model and Chapman–Enskog Approach for Heated Beryllium at Metallic Density Using Quantum Molecular Dynamics

We conducted a comprehensive analysis of quantum molecular dynamics (QMD) simulation results for beryllium (Be) at metallic density and temperatures up to 32,000 K. Using the QMD results for the radial distribution function (RDF), velocity autocorrelation function (VACF), mean-squared displacement (MSD), and the diffusion coefficient of ions, we confidently assess the effectiveness of the Yukawa one-component plasma model in describing ion structure and transport properties. Additionally, we analyzed the applicability and accuracy of the Chapman–Enskog method for calculating the diffusion coefficient. We found that Yukawa model-based molecular dynamics (MD) simulations accurately capture ion dynamics, as evidenced by the VACF and MSD, when the Yukawa potential parameters are correctly chosen. Through our comparative analysis of the QMD, Yukawa–MD, and Chapman–Enskog methods, we clearly identified the effective coupling parameter values at which the Chapman–Enskog method maintains its accuracy. Importantly, while a model that reproduces the RDF of ions may not guarantee precise transport properties, our findings underscore the necessity of benchmarking plasma models against QMD results from real materials to validate their applicability and efficacy.