Variational minimization scheme for the one-particle reduced density matrix functional theory in the ensemble N-representability domain

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Hauptverfasser: Vladaj, Matthieu, Marécat, Quentin, Senjean, Bruno, Saubanère, Matthieu
Format: Preprint
Veröffentlicht: 2024
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author Vladaj, Matthieu
Marécat, Quentin
Senjean, Bruno
Saubanère, Matthieu
author_facet Vladaj, Matthieu
Marécat, Quentin
Senjean, Bruno
Saubanère, Matthieu
contents The one-particle reduced density-matrix (1-RDM) functional theory is a promising alternative to density-functional theory (DFT) that uses the 1-RDM rather than the electronic density as a basic variable. However, long-standing challenges such as the lack of Kohn--Sham scheme and the complexity of the pure $N$-representability conditions are still impeding its wild utilization. Fortunately, ensemble $N$-representability conditions derived in the natural orbital basis are known and trivial, such that almost every functionals of the 1-RDM are actually natural orbital functionals which do not perform well for all the correlation regimes. In this work, we propose a variational minimization scheme in the ensemble $N$-representable domain that is not restricted to the natural orbital representation of the 1-RDM. We show that splitting the minimization into the diagonal and off-diagonal part of the 1-RDM can open the way toward the development of functionals of the orbital occupations, which remains a challenge for the generalization of site-occupation functional theory in chemistry. Our approach is tested on the uniform Hubbard model using the Müller and the Töws--Pastor functionals, as well as on the dihydrogen molecule using the Müller functional.
format Preprint
id arxiv_https___arxiv_org_abs_2405_10593
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Variational minimization scheme for the one-particle reduced density matrix functional theory in the ensemble N-representability domain
Vladaj, Matthieu
Marécat, Quentin
Senjean, Bruno
Saubanère, Matthieu
Quantum Physics
Strongly Correlated Electrons
The one-particle reduced density-matrix (1-RDM) functional theory is a promising alternative to density-functional theory (DFT) that uses the 1-RDM rather than the electronic density as a basic variable. However, long-standing challenges such as the lack of Kohn--Sham scheme and the complexity of the pure $N$-representability conditions are still impeding its wild utilization. Fortunately, ensemble $N$-representability conditions derived in the natural orbital basis are known and trivial, such that almost every functionals of the 1-RDM are actually natural orbital functionals which do not perform well for all the correlation regimes. In this work, we propose a variational minimization scheme in the ensemble $N$-representable domain that is not restricted to the natural orbital representation of the 1-RDM. We show that splitting the minimization into the diagonal and off-diagonal part of the 1-RDM can open the way toward the development of functionals of the orbital occupations, which remains a challenge for the generalization of site-occupation functional theory in chemistry. Our approach is tested on the uniform Hubbard model using the Müller and the Töws--Pastor functionals, as well as on the dihydrogen molecule using the Müller functional.
title Variational minimization scheme for the one-particle reduced density matrix functional theory in the ensemble N-representability domain
topic Quantum Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2405.10593