Molecular dynamics of nondegenerate hydrogen plasma using improved Kelbg pseudopotential with electron finite-size correction

TL;DR

This study improves semiclassical molecular dynamics simulations of nondegenerate hydrogen plasma by incorporating electron finite-size effects in the Kelbg pseudopotential, addressing nonphysical clustering and analyzing thermodynamic properties.

Contribution

The paper introduces an improved Kelbg pseudopotential with electron finite-size correction, reducing nonphysical clustering and enabling detailed plasma property analysis.

Findings

Finite-size correction prevents cluster formation below 50 kK.

Energy is underestimated at low temperatures compared to path integral Monte Carlo.

Long-range interactions significantly affect energy dependence on system size.

Abstract

This paper is devoted to semiclassical molecular dynamics simulation of nondegenerate hydrogen plasma using an improved Kelbg pseudopotential. The main novelty of our method is accounting for the finite size of electrons. This modification resolves the nonphysical cluster formation at temperatures below 50 kK, which was first reported by A.V. Filinov [Phys. Rev. E 70, 046411 (2004)]. However, the energy still appears to be underestimated at low temperatures, as indicated by comparisons with the recent path integral Monte Carlo calculations [Phys. Plasmas 31, 110501 (2024)]. Using the presented method, we analyze the dependence of radial distribution functions, composition, ionization degree, energy, and pressure on the plasma coupling parameter, while maintaining a fixed degeneracy parameter. Additionally, we demonstrate the impact of incorporating long-range interactions on the energy $N$-dependence by utilizing the angular-averaged Ewald potential. Finally, we compute the thermodynamic limits for energy and pressure.