Momentum distribution function and short-range correlations of the warm dense electron gas -- ab initio quantum Monte Carlo results

TL;DR

This paper provides ab initio quantum Monte Carlo results confirming the predicted algebraic decay of the momentum distribution in warm dense electron gases, highlighting the role of short-range correlations.

Contribution

First-principles fermionic path integral Monte Carlo simulations confirm the $k^{-8}$ decay of the momentum distribution in warm dense electron gases, linking it to short-range correlations.

Findings

Confirmed the $k^{-8}$ asymptotic decay of $n(k)$

Analyzed the density and temperature dependence of the on-top PDF

Provided extensive momentum distribution data across conditions

Abstract

In a classical plasma the momentum distribution, $n(k)$, decays exponentially, for large $k$, and the same is observed for an ideal Fermi gas. However, when quantum and correlation effects are relevant simultaneously, an algebraic decay, $n_\infty(k)\sim k^{-8}$ has been predicted. This is of relevance for cross sections and threshold processes in dense plasmas that depend on the number of energetic particles. Here we present extensive \textit{ab initio} results for the momentum distribution of the nonideal uniform electron gas at warm dense matter conditions. Our results are based on first principle fermionic path integral Monte Carlo (CPIMC) simulations and clearly confirm the $k^{-8}$ asymptotic. This asymptotic behavior is directly linked to short-range correlations which are analyzed via the on-top pair distribution function (on-top PDF), i.e. the PDF of electrons with opposite spin. We present extensive results for the density and temperature dependence of the on-top PDF and for the momentum distribution in the entire momentum range.