The driving force for Π-bond localization and bond alternation in trisannelated benzenes

2017 ◽  
Vol 19 (4) ◽  
pp. 3019-3027
Author(s):  
Xuhui Lin ◽  
Zhenhua Chen ◽  
Wei Wu
Keyword(s):  
Ab Initio ◽  
Driving Force ◽  
Valence Bond ◽  
Kekulé Structures ◽  
Bond Alternation ◽  
Bond Localization

Ab initio valence bond studies reveal different weights of the endo- and exo-Kekulé structures for trisannelated benzene.

The orthogonal valence bond interpretation of ab initio chemisorption cluster model wavefunctions

1993 ◽  
Vol 177 (1) ◽  
pp. 61-67 ◽  
Author(s):  
A. Clotet ◽  
J.M. Ricart ◽  
J. Rubio ◽  
F. Illas
Keyword(s):  
Ab Initio ◽  
Cluster Model ◽  
Valence Bond

Polaronic and Bipolaronic Enhancement of Second Hyperpolarizabilities in Dithienyl Polyenes from Ab Initio Quantum Methods

1999 ◽  
Vol 597 ◽  
Author(s):  
Steven Trohalaki ◽  
Robert J. Zellmer ◽  
Ruth Pachter
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Valence Bond ◽  
Closed Shell ◽  
Functional Theory ◽  
Molecular Conformations ◽  
Hartree Fock ◽  
Molecular Charge ◽  
Field Methodology ◽  
Moller Plesset

AbstractSpangler and He [1,2] have shown that dithienyl polyenes form extremely stable bipolaronic dications when oxidatively doped in solution. Previous theoretical studies applied empirical methods to predict bipolaronic enhancement of hyperpolarizabilities for simple polyenes [3,4]. Here, we employ density functional theory to optimize the gas-phase molecular conformations of neutral, cationic, and dicationic forms of a series of dithienyl polyenes, where the number of ethene units, N, is varied from 1–5. Ab initio Hartree-Fock, generalized valence bond, configuration interaction, and Møller-Plesset calculations demonstrate that the dications are farily well described with a closed shell and therefore have little biradicaloid character. Second hyperpolarizabilities, γ, are subsequently calculated using ab initio Hartree-Fock theory and a finite field methodology. As expected, γ increases with the number of ethene units for a given molecular charge. The cations also show the largest increase in γ with N. For a given value of N, the cations display the largest γ values. However, if we treat the dication as a triplet, which might be present in solution, then it displays the largest γ.

Ab Initio valence bond treatment of simple molecules

2009 ◽  
Vol 8 (S8) ◽  
pp. 285-291 ◽  
Author(s):  
M. Raimondi ◽  
G. F. Tantardini ◽  
M. Simonetta
Keyword(s):  
Ab Initio ◽  
Valence Bond ◽  
Simple Molecules

Covalent Excited States of Polyenes C2nH2n+2(n= 2−8) and Polyenyl Radicals C2n-1H2n+1(n= 2−8): An Ab Initio Valence Bond Study

2008 ◽  
Vol 4 (12) ◽  
pp. 2101-2107 ◽  
Author(s):  
Junjing Gu ◽  
Yonghui Lin ◽  
Ben Ma ◽  
Wei Wu ◽  
Sason Shaik
Keyword(s):  
Ab Initio ◽  
Excited States ◽  
Valence Bond

Tautomerism of protonated imidazoles: A perspective from ab initio valence bond theory

Tetrahedron ◽  
2018 ◽  
Vol 74 (37) ◽  
pp. 4791-4798 ◽  
Author(s):  
Huaiyu Zhang ◽  
Wei Wu ◽  
Yirong Mo
Keyword(s):  
Ab Initio ◽  
Valence Bond ◽  
Valence Bond Theory ◽  
Bond Theory

New problems for ab-initio valence bond theory

2009 ◽  
Vol 20 (S15) ◽  
pp. 225-229
Author(s):  
Massimo Simonetta ◽  
Mario Raimondi ◽  
Gian Franco Tantardini
Keyword(s):  
Ab Initio ◽  
Valence Bond ◽  
Valence Bond Theory ◽  
Bond Theory

On the generalized valence bond description of the anomeric and exo-anomeric effects: an ab initio conformational study of 2-methoxytetrahydropyran

2005 ◽  
Vol 340 (13) ◽  
pp. 2171-2184 ◽  
Author(s):  
Rodrigo S. Bitzer ◽  
André G.H. Barbosa ◽  
Clarissa O. da Silva ◽  
Marco A.C. Nascimento
Keyword(s):  
Ab Initio ◽  
Valence Bond ◽  
Conformational Study ◽  
Generalized Valence Bond ◽  
Anomeric Effects
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