Density functional theory (DFT) investigation of molecular structure and frontier molecular orbitals (FMOs) of P-N,N-dimethylaminobenzylidenemalononitrile (DBM)

2011 ◽  
Vol 79 (5) ◽  
pp. 1499-1504 ◽  
Author(s):  
M.M. El-Nahass ◽  
M.A. Kamel ◽  
A.F. El-Deeb ◽  
A.A. Atta ◽  
S.Y. Huthaily
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Molecular Orbitals ◽  
Frontier Molecular Orbitals ◽  
Functional Theory

THE INVESTIGATION ON ELECTRONIC PROPERTIES AND STABILITY OF POLYOXOMETALATES FUNCTIONALIZED BY ORGANOMETALLIC TITANIUM [CpTi · SiW9V3O40]4- BY DENSITY FUNCTIONAL THEORY

2009 ◽  
Vol 08 (04) ◽  
pp. 773-781 ◽  
Author(s):  
YANLING SI ◽  
WEILIN CHEN ◽  
ZHIMING ZHANG ◽  
ENBO WANG
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Molecular Orbitals ◽  
Frontier Molecular Orbitals ◽  
Functional Theory ◽  
Fragment Analysis ◽  
Keggin Type ◽  
System A ◽  
The Stability ◽  
Oxygen Atoms

The electronic structures of [ CpTi · SiW 9 V 3 O 40]4- constructed from Keggin–type polyoxometalates functionalized by CpTi 3+ group have been investigated by Density Functional Theory (DFT) methods. We discuss the relative stability affected by incorporating the CpTi 3+ group into the different sites of the [ SiW 9 V 3 O 40]7- framework on the basis of geometrical parameters, total bonding energies, fragment analysis and frontier molecular orbitals analysis. The calculated results indicated that the structure of the CpTi 3+ group coordinating to one terminal oxygen and two bridging oxygen atoms of the Keggin–type polyoxoanion (system a) is more stable than that to three bridging oxygen atoms (system b). In system a, Ti -Ob1, Ti -Ob2 and Ti - Ot1 are relatively shorter, and as result, it exhibits a more compact and nearly spherical structure of the well-known Keggin–type [ SiW 9 V 3 O 40]7-. Fragment analysis elucidates that there is deviation of ΔE B in systems a and b, which makes a significant contribution to the stability of system a. The stability of different isomeric forms of polyoxoanions appears to be a balance between the stabilizing ΔE O and ΔE E terms and the destabilizing ΔE P term. The relatively small energy differences (ΔE B = 4.26 eV ) between systems a and b arise directly from this balance. Frontier molecular orbitals analysis further confirms the stability order of systems a > b by the difference of the HOMO-LUMO energy gap.

Molecular Structures, Rotational Barriers, and Density Functional Theory Studies on 3,5-Diamino-6-(2,3-Dichlorophenyl)-1,2,4-Triazine

2019 ◽  
Vol 892 ◽  
pp. 185-192
Author(s):  
Pek Lan Toh ◽  
Suh Miin Wang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Molecular Orbitals ◽  
Geometrical Parameters ◽  
Atomic Charges ◽  
Frontier Molecular Orbitals ◽  
Dft Methods ◽  
Functional Theory ◽  
Rotational Barriers ◽  
Total Energies

In this report, different hybrid Density Functional Theory (DFT) methods were utilized to determine the geometries, total energies, Frontier molecular orbitals, atomic charges, and rotational barriers of 3,5-Diamino-6-(2,3-Dichlorophenyl)-1,2,4-Triazine, C9H7Cl2N5 molecular system. All optimized geometrical parameters (i.e. bond lengths, bond angles, and dihedral angles) were then compared with the experimental data, which reported by Sridhar and Ravikumar in 2009 [5]. Also, the results of electronic structures (i.e. total energies, Frontier molecular orbitals, atomic charges, and others) obtained by different DFT methods were compared and discussed.

Density Functional Theory Study on the Absorption of CO2 by the Ionic Liquid of 1-butyl-3-methylimidazolium Acetate

2013 ◽  
Vol 807-809 ◽  
pp. 543-548 ◽  
Author(s):  
Yan Fei Chen ◽  
Yan Hong Cui ◽  
Dong Shun Deng ◽  
Ning Ai
Keyword(s):  
Density Functional Theory ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Density Functional ◽  
Ion Pairs ◽  
Ion Pair ◽  
Frontier Molecular Orbitals ◽  
Density Functional Theory Study ◽  
Electronic Density ◽  
Functional Theory

The absorptions of CO2on the 1-butyl-3-methylimidazolium acetate ([Bmi [Ac]) with different substituents are calculated systematically at GGA/PW91 level. Three hydrogen bonds are formed between [A and cations of 1-n-[Bmi [A ([NBmi+) and 1-tert-[Bmi [A ([TBmi+). The interaction between CO2and the [NBmi [A by a C-O bond is much weaker than that with the [TBmi [A by forming a O...O...C...C four member-ring. The chemisorption of CO2on the ion pairs of [NBmi [A is much weaker than that on the [TBmi [A, resulted from the absorption energies analysis. The frontier molecular orbitals shows the electronic density overlap between absorbed CO2and the [A in CO2-[NBmi [A is much weaker than that in [TBmi [A. Therefore, the chemisorption of CO2on the ion pair of [NBmi [A is much weaker than that on the [TBmi [A. The ionic liquids based [NBmi+can be used repetitively, and the adsorbed CO2would be easier desorbed.

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