Electronic Density Response of Warm Dense Hydrogen: Ab initio Path Integral Monte Carlo Simulations

TL;DR

This paper provides highly accurate ab initio PIMC simulations of hydrogen's electronic density response under warm dense conditions, crucial for interpreting XRTS experiments and advancing theoretical models.

Contribution

It introduces the first unbiased PIMC results for hydrogen's electronic response and derives the exchange-correlation kernel relevant for TD-DFT applications.

Findings

Accurate PIMC data for hydrogen's density response

First unbiased calculation of the exchange-correlation kernel

Enhanced understanding of warm dense hydrogen properties

Abstract

The properties of hydrogen under extreme conditions are important for many applications, including inertial confinement fusion and astrophysical models. A key quantity is given by the electronic density response to an external perturbation, which is probed in X-ray Thomson scattering (XRTS) experiments -- the state of the art diagnostics from which system parameters like the free electron density $n_e$, the electronic temperature $T_e$, and the charge state $Z$ can be inferred. In this work, we present highly accurate path integral Monte Carlo (PIMC) results for the electronic density response of hydrogen. We obtain the exchange-correlation (XC) kernel $K_{xc}$, which is of central relevance for many applications, such as time-dependent density functional theory (TD-DFT). This gives us a first unbiased look into the electronic density response of hydrogen in the warm-dense matter regime, thereby opening up a gamut of avenues for future research.