Accelerated free energy estimation in ab initio path integral Monte Carlo simulations

Fuente: arXiv
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Autori principali: Svensson, Pontus, Kalkavouras, Fotios, Acosta, Uwe Hernandez, Moldabekov, Zhandos A., Tolias, Panagiotis, Vorberger, Jan, Dornheim, Tobias
Natura: Preprint
Pubblicazione: 2025
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author Svensson, Pontus
Kalkavouras, Fotios
Acosta, Uwe Hernandez
Moldabekov, Zhandos A.
Tolias, Panagiotis
Vorberger, Jan
Dornheim, Tobias
author_facet Svensson, Pontus
Kalkavouras, Fotios
Acosta, Uwe Hernandez
Moldabekov, Zhandos A.
Tolias, Panagiotis
Vorberger, Jan
Dornheim, Tobias
contents We present a methodology for accelerating the estimation of the free energy from path integral Monte Carlo simulations by considering an intermediate artificial reference system where interactions are inexpensive to evaluate numerically. Using the spherically averaged Ewald interaction as this intermediate reference system for the uniform electron gas, the interaction contribution for the free energy was evaluated up to 18 times faster than the Ewald-only method. Furthermore, a $ξ$-extrapolation technique was tested and applied to alleviate the fermion sign problem and to resolve the sign for large particle numbers. Combining these two techniques enabled the evaluation of the free energy for a system of 1000 electrons, where both finite-size and statistical errors are below chemical accuracy. The general procedure can be applied to systems relevant for planetary and inertial confinement fusion modeling with low to moderate levels of quantum degeneracy.
format Preprint
id arxiv_https___arxiv_org_abs_2507_12960
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Accelerated free energy estimation in ab initio path integral Monte Carlo simulations
Svensson, Pontus
Kalkavouras, Fotios
Acosta, Uwe Hernandez
Moldabekov, Zhandos A.
Tolias, Panagiotis
Vorberger, Jan
Dornheim, Tobias
Chemical Physics
Computational Physics
Plasma Physics
We present a methodology for accelerating the estimation of the free energy from path integral Monte Carlo simulations by considering an intermediate artificial reference system where interactions are inexpensive to evaluate numerically. Using the spherically averaged Ewald interaction as this intermediate reference system for the uniform electron gas, the interaction contribution for the free energy was evaluated up to 18 times faster than the Ewald-only method. Furthermore, a $ξ$-extrapolation technique was tested and applied to alleviate the fermion sign problem and to resolve the sign for large particle numbers. Combining these two techniques enabled the evaluation of the free energy for a system of 1000 electrons, where both finite-size and statistical errors are below chemical accuracy. The general procedure can be applied to systems relevant for planetary and inertial confinement fusion modeling with low to moderate levels of quantum degeneracy.
title Accelerated free energy estimation in ab initio path integral Monte Carlo simulations
topic Chemical Physics
Computational Physics
Plasma Physics
url https://arxiv.org/abs/2507.12960