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Title: Evaluation of the quasi correlated tight-binding (QCTB) model for describing polyradical character in polycyclic hydrocarbons
Authors: Luzanov, Anatoliy V.
Plasser, Felix
Das, Anita
Lischka, Hans
Issue Date: 2017
Publisher: AIP
Citation: LUZANOV, A.V. ...et al., 2017. Evaluation of the quasi correlated tight-binding (QCTB) model for describing polyradical character in polycyclic hydrocarbons. The Journal of Chemical Physics, 146: 064106.
Abstract: We present a verification and significant algorithmic improvement of the quasi-correlation tightbinding (QCTB) scheme (a H¨uckel-Hubbard-type model mimicking electron correlation) for describing effectively unpaired electrons in the spirit of Head-Gordon’s approach [M. Head-Gordon, Chem. Phys. Lett. 380, 488 (2003)]. For comparison purposes, results based on the high-level ab initio multireference averaged quadratic coupled cluster method previously computed in our works are invoked. In doing so, typical polyaromatic hydrocarbons (polyacenes, periacenes, zethrenes, and the Clar goblet) are studied. The evaluation shows that the QCTB H¨uckel-like scheme extended for electron correlation effects provides a qualitatively and in several cases also quantitatively good picture of the unpairing electrons in formally closed-shell electronic systems. Additionally, fairly large nanographene systems of triangulene structure (C426) and a perforated nanoribbon (C8860) have been treated at QCTB level. Two analytical model problems in the framework of QCTB prove the ability of this approximation to give a correct description of natural orbital occupancy spectra. For the studied QCTB scheme, an efficient algorithm is elaborated, and large-scale calculations of radical characteristics for nanographene networks with thousands of carbon atoms are possible.
Description: This paper was accepted for publication in the journal The Journal of Chemical Physics and the definitive published version is available at https://doi.org/10.1063/1.4975196
Sponsor: This material is based upon work supported by the National Science Foundation under Project No. CHE-1213263, by the Austrian Science Fund (SFB F41, ViCom), and by the VSC Research Center funded by the Austrian Federal Ministry of Science, Research and Economy (BMWFW).
Version: Published
DOI: 10.1063/1.4975196
URI: https://dspace.lboro.ac.uk/2134/32125
Publisher Link: https://doi.org/10.1063/1.4975196
ISSN: 0021-9606
Appears in Collections:Published Articles (Chemistry)

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