Molecular Properties in Quantum-Classical Auxiliary-Field Quantum Monte Carlo: Correlated Sampling with Application to Accurate Nuclear Forces

Fuente: arXiv
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Auteurs principaux: Goings, Joshua J., Shin, Kyujin, Noh, Seunghyo, Kyoung, Woomin, Kim, Donghwi, Baek, Jihye, Roetteler, Martin, Epifanovsky, Evgeny, Zhao, Luning
Format: Preprint
Publié: 2025
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author Goings, Joshua J.
Shin, Kyujin
Noh, Seunghyo
Kyoung, Woomin
Kim, Donghwi
Baek, Jihye
Roetteler, Martin
Epifanovsky, Evgeny
Zhao, Luning
author_facet Goings, Joshua J.
Shin, Kyujin
Noh, Seunghyo
Kyoung, Woomin
Kim, Donghwi
Baek, Jihye
Roetteler, Martin
Epifanovsky, Evgeny
Zhao, Luning
contents We extend correlated sampling from classical auxiliary-field quantum Monte Carlo to the quantum-classical (QC-AFQMC) framework, enabling accurate nuclear force computations crucial for geometry optimization and reaction dynamics. Stochastic electronic structure methods typically encounter prohibitive statistical noise when computing gradients via finite differences. To address this, our approach maximizes correlation between nearby geometries by synchronizing random number streams, aligning orbitals, using deterministic integral decompositions, and employing a consistent set of classical shadow measurements defined at a single reference geometry. Crucially, reusing this single, reference-defined shadow ensemble eliminates the need for additional quantum measurements at displaced geometries. Together, these methodological choices substantially reduce statistical variance in computed forces. We validate the method across hydrogen chains, confirming accuracy throughout varying correlation regimes, and demonstrate significant improvements over single-reference methods in force evaluations for N$_2$ and stretched linear H$_4$, particularly in strongly correlated regions where conventional coupled cluster approaches qualitatively fail. Orbital-optimized trial wave functions further boost accuracy for demanding cases such as stretched CO$_2$, without increasing quantum resource requirements. Finally, we apply our methodology to the MEA-CO$_2$ carbon capture reaction, employing quantum information metrics for active space selection and matchgate shadows for efficient overlap evaluations, establishing QC-AFQMC as a robust framework for exploring complex reaction pathways.
format Preprint
id arxiv_https___arxiv_org_abs_2507_17992
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Molecular Properties in Quantum-Classical Auxiliary-Field Quantum Monte Carlo: Correlated Sampling with Application to Accurate Nuclear Forces
Goings, Joshua J.
Shin, Kyujin
Noh, Seunghyo
Kyoung, Woomin
Kim, Donghwi
Baek, Jihye
Roetteler, Martin
Epifanovsky, Evgeny
Zhao, Luning
Quantum Physics
Chemical Physics
We extend correlated sampling from classical auxiliary-field quantum Monte Carlo to the quantum-classical (QC-AFQMC) framework, enabling accurate nuclear force computations crucial for geometry optimization and reaction dynamics. Stochastic electronic structure methods typically encounter prohibitive statistical noise when computing gradients via finite differences. To address this, our approach maximizes correlation between nearby geometries by synchronizing random number streams, aligning orbitals, using deterministic integral decompositions, and employing a consistent set of classical shadow measurements defined at a single reference geometry. Crucially, reusing this single, reference-defined shadow ensemble eliminates the need for additional quantum measurements at displaced geometries. Together, these methodological choices substantially reduce statistical variance in computed forces. We validate the method across hydrogen chains, confirming accuracy throughout varying correlation regimes, and demonstrate significant improvements over single-reference methods in force evaluations for N$_2$ and stretched linear H$_4$, particularly in strongly correlated regions where conventional coupled cluster approaches qualitatively fail. Orbital-optimized trial wave functions further boost accuracy for demanding cases such as stretched CO$_2$, without increasing quantum resource requirements. Finally, we apply our methodology to the MEA-CO$_2$ carbon capture reaction, employing quantum information metrics for active space selection and matchgate shadows for efficient overlap evaluations, establishing QC-AFQMC as a robust framework for exploring complex reaction pathways.
title Molecular Properties in Quantum-Classical Auxiliary-Field Quantum Monte Carlo: Correlated Sampling with Application to Accurate Nuclear Forces
topic Quantum Physics
Chemical Physics
url https://arxiv.org/abs/2507.17992