# Permutation Blocking Path Integral Monte Carlo approach to the Static Density Response of the Warm Dense Electron Gas

## TL;DR

This paper employs an advanced permutation blocking path integral Monte Carlo method to accurately compute the static density response of the warm dense electron gas, highlighting the importance of exact correlation treatments.

## Contribution

The study introduces the application of PB-PIMC to the warm dense electron gas, providing highly accurate ab initio results for the static density response and local field correction.

## Key findings

- PB-PIMC yields highly accurate static density response functions.
- Comparison shows dielectric approximations are insufficient without exact correlations.
- Multiple perturbations analysis informs static response calculations.

## Abstract

The static density response of the uniform electron gas is of fundamental importance for numerous applications. Here, we employ the recently developed \textit{ab initio} permutation blocking path integral Monte Carlo (PB-PIMC) technique [T.~Dornheim \textit{et al.}, \textit{New J.~Phys.}~\textbf{17}, 073017 (2015)] to carry out extensive simulations of the harmonically perturbed electron gas at warm dense matter conditions. In particular, we investigate in detail the validity of linear response theory and demonstrate that PB-PIMC allows to obtain highly accurate results for the static density response function and, thus, the static local field correction. A comparison with dielectric approximations to our new \textit{ab initio} data reveals the need for an exact treatment of correlations. Finally, we consider a superposition of multiple perturbations and discuss the implications for the calculation of the static response function.