Second roton feature in the strongly coupled electron liquid
Abstract
We present extensive \emph{ab initio} path integral Monte Carlo (PIMC) results for the dynamic properties of the finite temperature uniform electron gas (UEG) over a broad range of densities, . We demonstrate that the direct analysis of the imaginary-time density--density correlation function (ITCF) allows for a rigorous assessment of the density and temperature dependence of the previously reported roton-type feature [T.~Dornheim, \emph{Phys.~Rev.~Lett.}~\textbf{121}, 255001 (2018)] at intermediate wavenumbers. We clearly resolve the emergence of a second roton at the second harmonic of the original feature for , which we identify as an incipient phonon dispersion. Finally, we use our highly accurate PIMC results for the ITCF as the basis for an analytic continuation to compute the dynamic structure factor, which additionally substantiates the existence of the second roton in the strongly coupled electron liquid. Our investigation further elucidates the complex interplay between quantum delocalization and Coulomb coupling in the UEG. All PIMC results are freely available online and provide valuable benchmarks for other theoretical methodologies and approximations.
Cite
@article{arxiv.2505.11150,
title = {Second roton feature in the strongly coupled electron liquid},
author = {Thomas M. Chuna and Jan Vorberger and Panagiotis Tolias and Alexander Benedix Robles and Michael Hecht and Phil-Alexander Hofmann and Zhandos A. Moldabekov and Tobias Dornheim},
journal= {arXiv preprint arXiv:2505.11150},
year = {2025}
}