Static Response of the Strongly Coupled Electron Gas from Diffusion Monte Carlo
Abstract
The local field factor G(q) of the HEG describes how exchange and correlation modify the response to a static perturbation, and enters dielectric screening, effective electron--electron interactions, and the xc kernel of TDDFT. Accurate zero-temperature data for G(q), however, remain limited to metallic densities, rs≤10. In this work, we present diffusion Monte Carlo calculations of the static density response function χ(q) and of G(q) for 2≤ rs≤100, and describe and discuss the methodological steps that enabled these calculations. We show how optimization of the perturbing potential in the trial wave function has an important effect, as a poor choice can reverse the sign of the response. A closed-form expression is provided for its optimal value, together with the density dependence of the linear-response window. We further show that backflow correlations leave χ(q) unchanged and that G(q) depends only weakly on system size even at very low density, so that Slater--Jastrow wave functions and modest system sizes suffice. Together, these results provide a practical guide for future QMC calculations of response properties of the electron gas and real materials. Our results agree with previous DMC data at metallic densities for q>kF, and extend them below kF. They also agree with diagrammatic QMC at rs=2. At lower densities, our results show that G(q) develops a nonmonotonic structure at intermediate-q, where the response approaches that of the noninteracting gas. Quantitative agreement is seen with finite-temperature path integral Monte Carlo, suggesting that the previously reported finite-temperature structure is inherited from the ground state. Using a parametrization of G(q) that reproduces our data throughout the liquid phase, we relate this structure to short-range order in the pair correlation function and the static structure factor.
Related
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BibTeX
@misc{gunes2026static,
title = {{Static Response of the Strongly Coupled Electron Gas from Diffusion Monte Carlo}},
author = {Muhammed H. Güneş and Yubo Yang and Vitaly Gorelov and Miguel A. Morales and Matteo Gatti and Lucia Reining and Shiwei Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.40093},
eprint = {2610.40093},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.40093},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Static Response of the Strongly Coupled Electron Gas from Diffusion Monte Carlo
AU - Muhammed H. Güneş
AU - Yubo Yang
AU - Vitaly Gorelov
AU - Miguel A. Morales
AU - Matteo Gatti
AU - Lucia Reining
AU - Shiwei Zhang
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.40093
UR - https://arxiv.org/abs/2610.40093
AB - The local field factor G(q) of the HEG describes how exchange and correlation modify the response to a static perturbation, and enters dielectric screening, effective electron--electron interactions, and the xc kernel of TDDFT. Accurate zero-temperature data for G(q), however, remain limited to metallic densities, r_s≤10. In this work, we present diffusion Monte Carlo calculations of the static density response function χ(q) and of G(q) for 2≤ r_s≤100, and describe and discuss the methodological steps that enabled these calculations. We show how optimization of the perturbing potential in the trial wave function has an important effect, as a poor choice can reverse the sign of the response. A closed-form expression is provided for its optimal value, together with the density dependence of the linear-response window. We further show that backflow correlations leave χ(q) unchanged and that G(q) depends only weakly on system size even at very low density, so that Slater--Jastrow wave functions and modest system sizes suffice. Together, these results provide a practical guide for future QMC calculations of response properties of the electron gas and real materials. Our results agree with previous DMC data at metallic densities for q>k_F, and extend them below k_F. They also agree with diagrammatic QMC at r_s=2. At lower densities, our results show that G(q) develops a nonmonotonic structure at intermediate-q, where the response approaches that of the noninteracting gas. Quantitative agreement is seen with finite-temperature path integral Monte Carlo, suggesting that the previously reported finite-temperature structure is inherited from the ground state. Using a parametrization of G(q) that reproduces our data throughout the liquid phase, we relate this structure to short-range order in the pair correlation function and the static structure factor.
ER -