Non-iterative Triples for Transcorrelated Coupled Cluster Theory

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Auteurs principaux: Mörchen, Maximilian, Baiardi, Alberto, Lesiuk, Michał, Reiher, Markus
Format: Preprint
Publié: 2024
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author Mörchen, Maximilian
Baiardi, Alberto
Lesiuk, Michał
Reiher, Markus
author_facet Mörchen, Maximilian
Baiardi, Alberto
Lesiuk, Michał
Reiher, Markus
contents We present an implementation of a perturbative triples correction for the coupled cluster ansatz including single and double excitations based on the transcorrelated Hamiltonian. Transcorrelation introduces explicit electron correlation in the electronic Hamiltonian through similarity transformation with a correlation factor. Due to this transformation, the transcorrelated Hamiltonian includes up to three-body couplings and becomes non-Hermitian. Since the conventional coupled cluster equations are solved by projection, it is well suited to harbor non-Hermitian Hamiltonians. The arising three-body operator, however, creates a huge memory bottleneck and increases the runtime scaling of the coupled cluster equations. As it has been shown that the three-body operator can be approximated, by expressing the Hamiltonian in the normal-ordered form, we investigate this approximation for the perturbative triples correction. Results are compared with a code-generation based transcorrelated coupled cluster implementation up to quadruple excitations.
format Preprint
id arxiv_https___arxiv_org_abs_2408_07858
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-iterative Triples for Transcorrelated Coupled Cluster Theory
Mörchen, Maximilian
Baiardi, Alberto
Lesiuk, Michał
Reiher, Markus
Chemical Physics
Strongly Correlated Electrons
Atomic Physics
Computational Physics
We present an implementation of a perturbative triples correction for the coupled cluster ansatz including single and double excitations based on the transcorrelated Hamiltonian. Transcorrelation introduces explicit electron correlation in the electronic Hamiltonian through similarity transformation with a correlation factor. Due to this transformation, the transcorrelated Hamiltonian includes up to three-body couplings and becomes non-Hermitian. Since the conventional coupled cluster equations are solved by projection, it is well suited to harbor non-Hermitian Hamiltonians. The arising three-body operator, however, creates a huge memory bottleneck and increases the runtime scaling of the coupled cluster equations. As it has been shown that the three-body operator can be approximated, by expressing the Hamiltonian in the normal-ordered form, we investigate this approximation for the perturbative triples correction. Results are compared with a code-generation based transcorrelated coupled cluster implementation up to quadruple excitations.
title Non-iterative Triples for Transcorrelated Coupled Cluster Theory
topic Chemical Physics
Strongly Correlated Electrons
Atomic Physics
Computational Physics
url https://arxiv.org/abs/2408.07858