Phaseless auxiliary-field quantum Monte Carlo method for cavity-QED matter systems

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Hauptverfasser: Weber, Lukas, Cunha, Leonardo dos Anjos, Morales, Miguel A., Rubio, Angel, Zhang, Shiwei
Format: Preprint
Veröffentlicht: 2024
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author Weber, Lukas
Cunha, Leonardo dos Anjos
Morales, Miguel A.
Rubio, Angel
Zhang, Shiwei
author_facet Weber, Lukas
Cunha, Leonardo dos Anjos
Morales, Miguel A.
Rubio, Angel
Zhang, Shiwei
contents We present a generalization of the phaseless auxiliary-field quantum Monte Carlo (AFQMC) method to cavity quantum-electrodynamical (QED) matter systems. The method can be formulated in both the Coulomb and the dipole gauge. We verify its accuracy by benchmarking calculations on a set of small molecules against full configuration interaction and state-of-the-art QED coupled cluster (QED-CCSD) calculations. Our results show that (i) gauge invariance can be achieved within correlation-consistent Gaussian basis sets, (ii) the accuracy of QED-CCSD can be enhanced significantly by adding the standard perturbative triples correction without light-matter coupling, and (iii) there is a straightforward way to evaluate the differential expression for the photon occupation number that works in any gauge. The high accuracy and favorable computational scaling of our AFQMC approach will enable a broad range of applications. Besides polaritonic chemistry, the method opens a way to simulate extended QED matter systems.
format Preprint
id arxiv_https___arxiv_org_abs_2410_18838
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Phaseless auxiliary-field quantum Monte Carlo method for cavity-QED matter systems
Weber, Lukas
Cunha, Leonardo dos Anjos
Morales, Miguel A.
Rubio, Angel
Zhang, Shiwei
Chemical Physics
We present a generalization of the phaseless auxiliary-field quantum Monte Carlo (AFQMC) method to cavity quantum-electrodynamical (QED) matter systems. The method can be formulated in both the Coulomb and the dipole gauge. We verify its accuracy by benchmarking calculations on a set of small molecules against full configuration interaction and state-of-the-art QED coupled cluster (QED-CCSD) calculations. Our results show that (i) gauge invariance can be achieved within correlation-consistent Gaussian basis sets, (ii) the accuracy of QED-CCSD can be enhanced significantly by adding the standard perturbative triples correction without light-matter coupling, and (iii) there is a straightforward way to evaluate the differential expression for the photon occupation number that works in any gauge. The high accuracy and favorable computational scaling of our AFQMC approach will enable a broad range of applications. Besides polaritonic chemistry, the method opens a way to simulate extended QED matter systems.
title Phaseless auxiliary-field quantum Monte Carlo method for cavity-QED matter systems
topic Chemical Physics
url https://arxiv.org/abs/2410.18838