Ab initio density functional theory approach to warm dense hydrogen: from density response to electronic correlations

TL;DR

This paper introduces a novel approach combining time-dependent and static density functional theory to accurately estimate electron-electron correlations in warm dense hydrogen, aiding astrophysical and fusion research.

Contribution

The authors develop a new method that integrates dynamic structure factor data with static DFT to improve the accuracy of electronic correlation estimates in warm dense matter.

Findings

High-accuracy estimation of $S_{ee}(q)$ across various densities and temperatures.

Addresses limitations of traditional thermal DFT in modeling electronic correlations.

Provides a new framework for future electronic correlation studies within DFT.

Abstract

Understanding the properties of warm dense hydrogen is of key importance for the modeling of compact astrophysical objects and to understand and further optimize inertial confinement fusion (ICF) applications. The work horse of warm dense matter theory is given by thermal density functional theory (DFT), which, however, suffers from two limitations: (i) its accuracy can depend on the utilized exchange--correlation (XC) functional, which has to be approximated and (ii) it is generally limited to single-electron properties such as the density distribution. Here, we present a new ansatz combining time-dependent DFT results for the dynamic structure factor $S_{ee}(\mathbf{q},\omega)$ with static DFT results for the density response. This allows us to estimate the electron--electron static structure factor $S_{ee}(\mathbf{q})$ of warm dense hydrogen with high accuracy over a broad range of densities and temperatures. In addition to its value for the study of warm dense matter, our work opens up new avenues for the future study of electronic correlations exclusively within the framework of DFT for a host of applications.