Correlations Between Conduction Electrons in Dense Plasmas

TL;DR

This paper develops a new theoretical framework to accurately describe electron-electron correlations in dense plasmas, incorporating ionic structure and quantum effects, with results validated against simulations and implications for plasma conductivity.

Contribution

It introduces a novel formula for the electron-electron static structure factor that accounts for ionic and quantum effects, extending quantum Ornstein-Zernike theory for dense plasmas.

Findings

Good agreement with path integral Monte Carlo simulations

Deviations from Debye-Hückel screening at relevant conditions

Correlations likely affect plasma conductivity and excitation processes

Abstract

Most treatments of electron-electron correlations in dense plasmas either ignore them entirely (random phase approximation) or neglect the role of ions (jellium approximation). In this work, we go beyond both these approximations to derive a new formula for the electron-electron static structure factor which properly accounts for the contributions of both ionic structure and quantum-mechanical dynamic response in the electrons. The result can be viewed as a natural extension of the quantum Ornstein-Zernike theory of ionic and electronic correlations, and it is suitable for dense plasmas in which the ions are classical and the conduction electrons are quantum-mechanical. The corresponding electron-electron pair distribution functions are compared with the results of path integral Monte Carlo simulations, showing good agreement whenever no strong electron resonance states are present. We construct approximate potentials of mean force which describe the effective screened interaction between electrons. Significant deviations from Debye-H\"uckel screening are present at temperatures and densities relevant to high energy density experiments involving warm and hot dense plasmas. The presence of correlations between conduction electrons is likely to influence the electron-electron contribution to the electron and thermal conductivity. It is expected that excitation processes involving the conduction electrons (e.g., free-free absorption) will also be affected.