Improving dynamic collision frequencies: impacts on dynamic structure factors and stopping powers in warm dense matter

TL;DR

This paper investigates how variations in dynamic electron-ion collision frequencies affect the properties of warm dense matter, impacting observable spectra and stopping powers, and improves modeling accuracy by incorporating detailed collision effects.

Contribution

It introduces a systematic analysis of collision frequency variations using a self-consistent average-atom model, enhancing agreement with first-principles simulations.

Findings

Including quantum density of states, strong, and inelastic collisions significantly alters collision frequencies.

These modifications cause observable shifts and broadening in the dynamic structure factor.

The improved model aligns better with time-dependent density functional theory results.

Abstract

Simulations and diagnostics of high-energy-density plasmas and warm dense matter rely on models of material response properties, both static and dynamic (frequency-dependent). Here, we systematically investigate variations in dynamic electron-ion collision frequencies $\nu(\omega)$ in warm dense matter using data from a self-consistent-field average-atom model. We show that including the full quantum density of states, strong collisions, and inelastic collisions lead to significant changes in $\nu(\omega)$. These changes result in red shifts and broadening of the plasmon peak in the dynamic structure factor, an effect observable in x-ray Thomson scattering spectra, and modify stopping powers around the Bragg peak. These changes improve the agreement of computationally efficient average-atom models with first-principles time-dependent density functional theory in warm dense aluminum, carbon, and deuterium.