Ab initio results for the plasmon dispersion and damping of the warm dense electron gas

TL;DR

This paper presents ab initio calculations of the plasmon dispersion and damping in warm dense electron gas, revealing significant deviations from traditional models and highlighting the importance of correlations and finite temperature effects.

Contribution

It provides the first ab initio analysis of the dynamic dielectric function and plasmon properties in warm dense matter, improving understanding beyond RPA and earlier models.

Findings

Significant differences from RPA in plasmon dispersion and damping.

Identification of breakdown points for weak damping approximations.

Complex zeros method effectively addresses damping issues.

Abstract

Warm dense matter (WDM) is an exotic state on the border between condensed matter and dense plasmas. Important occurrences of WDM include dense astrophysical objects, matter in the core of our Earth, as well as matter produced in strong compression experiments. As of late, x-ray Thomson scattering has become an advanced tool to diagnose WDM. The interpretation of the data requires model input for the dynamic structure factor $S(q,\omega)$ and the plasmon dispersion $\omega(q)$. Recently the first \textit{ab initio} results for $S(q,\omega)$ of the homogeneous warm dense electron gas were obtained from path integral Monte Carlo simulations, [Dornheim \textit{et al.}, Phys. Rev. Lett. \textbf{121}, 255001 (2018)]. Here, we analyse the effects of correlations and finite temperature on the dynamic dielectric function and the plasmon dispersion. Our results for the plasmon dispersion and damping differ significantly from the random phase approximation and from earlier models of the correlated electron gas. Moreover, we show when commonly used weak damping approximations break down and how the method of complex zeros of the dielectric function can solve this problem for WDM conditions.