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

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, and 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, ω) and the plasmon dispersion ω(q). Recently, the first ab initio results for S(q, ω) of the homogeneous warm dense electron gas were obtained from path integral Monte Carlo simulations (Dornheim et al., Phys. Rev. Lett., 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 zeroes of the dielectric function can solve this problem for WDM conditions.

Thermal excitation signals in the inhomogeneous warm dense electron gas

“…The choice of amplitude and wave number of the perturbation is grounded in our interest of inhomogeneities on excitations which become relevant when 83 . We therefore consider in the range from 0.1 to 1.0 and .…”

Quantum kinetic theory of plasmas

“…Thirdly, we stress that we here have focused on nondissipative quantum kinetic models, ignoring the effects of higher order correlation in the BBGKY-hierarchy, neglecting all the influence of collisions, as can be covered, e.g., by path integral quantum monte carlo methods (Dornheim et al 2018;Hamann et al 2020;Zhang et al 2016). However, the effect of dissipation is a broad research topic in its own right, of particular importance in the strong coupling regime.…”

“…Before ending this subsection, we point out that although the scaling is not exactly the same, nevertheless, electron correlations often are significant at the same time as exchange effects. A way to cover both strong coupling effects (electron correlations) and exchange effects beyond the mean-field level is the path integral quantum Monte Carlo approach (Dornheim et al 2018;Hamann et al 2020;Zhang et al 2016). In particular, results for the dynamic structure factor, closely related to the Langmuir susceptibility, have been presented in Refs (Dornheim et al 2018;Hamann et al 2020).…”

Screening of a test charge in a free‐electron gas at warm dense matter and dense non‐ideal plasma conditions

“…[ 7–9 ] New experimental data on WDM and partially degenerate dense plasmas have been motivating fast development of theoretical methods and investigations. [ 10–12 ] Particularly, the progress in Quantum Monte Carlo (QMC) simulations of electrons at WDM and dense plasma parameters [ 13–25 ] has allowed a systematic revision and further exploration of various fundamental plasma properties, such as the plasmon dispersion, [ 26 ] stopping power, [ 27 ] and thermodynamic properties. [ 11 ] Continuing the investigation of the electronic properties in the regime related to WDM and dense non‐ideal plasmas, in this paper we investigate the screening around a test charge (a fixed ion) in a free electron gas computed using the recent neural‐net representation of the static local field correction based on ab initio QMC simulations [ 13 ] within linear response theory.…”