X-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified...

Area of Science:

• Computational Physics
• Materials Science
• Plasma Physics

Background:

• X-ray Thomson scattering (XT) is a powerful diagnostic for dense plasmas.
• Accurate theoretical models are crucial for interpreting XT spectra.
• Existing models struggle with complex plasma conditions like pressure ionization.

Purpose of the Study:

• To develop and validate ab initio approaches for XT spectra calculations.
• To compare Mermin dielectric function models with linear-response time-dependent density functional theory (LR-TDDFT).
• To reanalyze experimental XT data for beryllium under varying plasma conditions.

Main Methods:

• Density functional theory molecular dynamics simulations.
• Modified Chihara formula incorporating dielectric functions.
• Ab initio electron-ion collision frequency calculations.
• Comparison between Mermin and LR-TDDFT dielectric functions.

Main Results:

• LR-TDDFT provides a more accurate description of the electronic dynamic structure factor than Mermin models, especially under compression.
• Mermin models show limitations when bound states become pressure ionized.
• Reanalysis of beryllium XT experiments reveals significant deviations from traditional models at low scattering angles.

Conclusions:

• LR-TDDFT is a superior method for calculating XT spectra in dense plasmas.
• This work highlights the limitations of analytic models for highly compressed matter.
• Accurate XT spectral analysis using advanced theoretical methods is essential for understanding plasma properties.