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Unitary coupled clu...
Unitary coupled cluster ground- and excited-state molecular properties
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- Hodecker, Manuel (author)
- KTH,Teoretisk kemi och biologi,Heidelberg Univ, Interdisciplinary Ctr Sci Comp, Neuenheimer Feld 205, D-69120 Heidelberg, Germany.
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- Dreuw, Andreas (author)
- Heidelberg Univ, Interdisciplinary Ctr Sci Comp, Neuenheimer Feld 205, D-69120 Heidelberg, Germany.
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(creator_code:org_t)
- AIP Publishing, 2020
- 2020
- English.
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 153:8
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- A scheme for the calculation of molecular properties within the framework of unitary coupled-cluster (UCC) theory in both the electronic ground and excited states is presented. The scheme is based on an expectation-value ansatz, similar to the equation-of-motion coupled-cluster method or the intermediate state representation (ISR) approach of the algebraic-diagrammatic construction (ADC) scheme. Due to the UCC ansatz, the resulting equations cannot be given by closed-form expressions but need to be approximated. Explicit expressions for the expectation value of a general one-particle operator correct through second order in perturbation theory have been derived and coded for the electronic ground state as well as for excited states of predominant single-excitation character. The resulting equations are shown to be equivalent to those of the second-order ADC/ISR procedure. As first computational tests, the second-order UCC method (UCC2) and the one employing third-order amplitudes (also eigenvectors) together with the second-order density matrix, denoted as UCC3(2), are applied to the calculation of dipole moments for a series of small closed- and open-shell systems as well as 4-cyanoindole and 2,3-benzofuran and compared to full configuration interaction or experimental results. For the aromatic organic molecules, the UCC2 method is shown to be sufficient for the ground-state dipole moment, whereas the UCC3(2) scheme is superior for excited-state dipole moments.
Subject headings
- NATURVETENSKAP -- Kemi -- Teoretisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)
Publication and Content Type
- ref (subject category)
- art (subject category)
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