scholarly journals Closed-shell paramagnetic porphyrinoids

2017 ◽  
Vol 53 (71) ◽  
pp. 9866-9869 ◽  
Author(s):  
Rashid R. Valiev ◽  
Heike Fliegl ◽  
Dage Sundholm
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Current ◽  
Closed Shell ◽  
Current Strength ◽  
Second Order ◽  
Functional Theory ◽  
Hartree Fock ◽  
Moller Plesset

Magnetizabilities and magnetically induced ring-current strength susceptibilities have been calculated at the Hartree–Fock, density functional theory and second order Møller–Plesset levels for a number of antiaromatic closed-shell carbaporphyrins, carbathiaporphyrins and isophlorins.

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.

Protonation Effect on C-N Bond Length of Alkylamines Studied by Molecular Orbital Calculations

2000 ◽  
Vol 55 (9-10) ◽  
pp. 769-771 ◽  
Keyword(s):  
Density Functional Theory ◽  
Bond Length ◽  
Molecular Orbital ◽  
Density Functional ◽  
Second Order ◽  
Basis Set ◽  
Molecular Orbital Calculations ◽  
Functional Theory ◽  
Hartree Fock ◽  
Protonation Effect

Abstract Molecular orbital calculations were performed for the six saturated alkylamines (CH3NH2 , (CH3)2 NH, (CH 3)3 N, CH 3CH2NH2 , (CH3)2 CHNH2 , (CH3)3 CNH2), their protonated cations (CH3NH3 + , (CH3)2NH2 + , (CH3)3NH + , CH3CH2NH3 + , (CH3)2CHNH3 + , (CH3)3CNH3+), and (CH3)4 N + using the Hartree-Fock, second-order M0ller-Plesset, and density functional theory methods with the 6-311+G(d,p) basis set. Protonation lengthens the C-N bonds of the amines by 0.05 -0.08 Å and shortens the C-C bonds of CH3CH2NH2, (CH3)2CHNH2 , and (CH3)3CNH2 by ca. 0.01 Å.

Quadrupole polarizabilities and Sternheimer antishielding factors in the density functional theory

1982 ◽  
Vol 60 (2) ◽  
pp. 210-221 ◽  
Author(s):  
M. J. Stott ◽  
E. Zaremba ◽  
D. Zobin
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Correlation Energy ◽  
Local Density ◽  
Closed Shell ◽  
Energy Functional ◽  
Functional Theory ◽  
Hartree Fock ◽  
Shielding Factor ◽  
The Density Functional Theory

The quadrupole polarizability and Sternheimer antishielding factor have been calculated for selected closed-shell atoms and ions using the density functional theory. In most cases, the results agree favourably with coupled Hartree–Fock calculations. However, for atoms with valence (d-shells the local density approximation used in the calculations is found to be inadequate. Our results suggest that refinements to the exchange-correlation energy functional are required in order to obtain accurate values for the polarizability and shielding factor of (d-shell atoms within a density functional approach.

Amine-Catalyzed B−O−C Bond Formation:  Mechanistic Insights from Density Functional Theory and Second-Order Møller−Plesset Perturbation Theory

2006 ◽  
Vol 25 (10) ◽  
pp. 2427-2436
Author(s):  
Krishna L. Bhat ◽  
Jack H. Lai ◽  
George D. Markham ◽  
Anthony M. DiJulio ◽  
Charles W. Bock
Keyword(s):  
Density Functional Theory ◽  
Perturbation Theory ◽  
Density Functional ◽  
Bond Formation ◽  
Second Order ◽  
Functional Theory ◽  
Moller Plesset ◽  
Plesset Perturbation Theory
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