Quasi-variational coupled-cluster theory: Performance of perturbative treatments of connected triple excitations

Black, Joshua A. and Knowles, Peter J. ORCID: https://orcid.org/0000-0003-4657-6331 2018. Quasi-variational coupled-cluster theory: Performance of perturbative treatments of connected triple excitations. Journal of Chemical Physics 148 (19) , -. 10.1063/1.5006037

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Abstract

Quasi-variational coupled-cluster methods are applied to a selection of diatomic molecules. The potential energy curves, spectroscopic constants, and size consistency errors are calculated and compared to those obtained from both single- and multi-reference methods. The effects of connected triple excitations are introduced with either the standard perturbative (T) formulation, or in the renormalised form, and its symmetrised approximation. It is found that the renormalised ansatz is significantly superior to the standard formulation when describing bond breaking and that in most circumstances, the computationally simpler symmetrisation gives nearly identical results.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Chemistry Advanced Research Computing @ Cardiff (ARCCA)
Publisher:	American Institute of Physics (AIP)
ISSN:	0021-9606
Funders:	EPSRC
Date of First Compliant Deposit:	23 May 2018
Date of Acceptance:	26 April 2018
Last Modified:	04 May 2023 18:16
URI:	https://orca.cardiff.ac.uk/id/eprint/111686

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