PMID- 28201909
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20180607
LR  - 20180607
IS  - 1089-7690 (Electronic)
IS  - 0021-9606 (Linking)
VI  - 146
IP  - 6
DP  - 2017 Feb 14
TI  - Evaluation of the quasi correlated tight-binding (QCTB) model for describing 
      polyradical character in polycyclic hydrocarbons.
PG  - 064106
LID - 10.1063/1.4975196 [doi]
AB  - We present a verification and significant algorithmic improvement of the 
      quasi-correlation tight-binding (QCTB) scheme (a Huckel-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 Huckel-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 (C(426)) and a perforated nanoribbon (C(8860)) 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.
FAU - Luzanov, Anatoliy V
AU  - Luzanov AV
AD  - SSI "Institute for Single Crystals," National Academy of Sciences of Ukraine, 60 
      Nauky Ave., 61001 Kharkiv, Ukraine.
FAU - Plasser, Felix
AU  - Plasser F
AUID- ORCID: 000000030751148X
AD  - Institute for Theoretical Chemistry, University of Vienna, Wahringerstrasse 17, 
      A-1090 Vienna, Austria.
FAU - Das, Anita
AU  - Das A
AD  - Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle 
      & Boston, Lubbock, Texas 79409, USA.
FAU - Lischka, Hans
AU  - Lischka H
AUID- ORCID: 0000000256563975
AD  - Department of Chemistry and Biochemistry, Texas Tech University, Memorial Circle 
      & Boston, Lubbock, Texas 79409, USA.
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Chem Phys
JT  - The Journal of chemical physics
JID - 0375360
EDAT- 2017/02/17 06:00
MHDA- 2017/02/17 06:01
CRDT- 2017/02/17 06:00
PHST- 2017/02/17 06:00 [entrez]
PHST- 2017/02/17 06:00 [pubmed]
PHST- 2017/02/17 06:01 [medline]
AID - 10.1063/1.4975196 [doi]
PST - ppublish
SO  - J Chem Phys. 2017 Feb 14;146(6):064106. doi: 10.1063/1.4975196.