Conjugated polymers: A systematic investigation of their electronic and geometric properties using density functional theory and semi-empirical methods

2018 ◽  
Vol 246 ◽  
pp. 128-136 ◽  
Author(s):  
Khanh B. Vu ◽  
Van V. Vu ◽  
Huong Phung Thi Thu ◽  
Ha N. Giang ◽  
Nguyen Minh Tam ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Conjugated Polymers ◽  
Density Functional ◽  
Systematic Investigation ◽  
Empirical Methods ◽  
Functional Theory ◽  
Geometric Properties ◽  
Semi Empirical

scholarly journals STRUCTURAL AND ELECTRONIC PROPERTIES OF BRIDGED BITHIOPHENE S-OXIDES (BTO) WITH S, S=O, O, SiH2 and BH2 BRIDGE: SEMI-EMPIRICAL AND AB INITIO STUDY

2010 ◽  
Vol 18 (18) ◽  
pp. 1-10
Author(s):  
Banjo Semire ◽  
Isaiah Ajibade Adejoro ◽  
Olusegun Ayobami Odunola
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Study ◽  
Empirical Methods ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical ◽  
Good Agreement

In this paper, we theoretically studied the geometries, stabilities, electronic and thermodynamic properties of bridged bithiophene S-oxide (BTO-X) derivates (with X = BH2, SiH2, S, S=O, and O) by using semi-empirical methods, ab-initio, and Density functional theory. The geometries and thermodynamic parameters calculated by PM3 were in good agreement with that of B3LYP/6-31G(d). The bandgap calculated by B3LYP/6-31G(d) ranged from 3.94eV (BTO-O)-3.16eV (BTO-BH2). The absorption λmax calculated suing B3LYP/6-31G(d) shifted to longer wavelength with X=BH2, SiH2, and S=O due to enhancement of π-conjugated system whereas, BTO-S and BTO-O shifted to shorter wavelengths as compared to dimmer thiophene S-oxide (2TO).

scholarly journals Density functional tight binding: values of semi-empirical methods in an ab initio era

2014 ◽  
Vol 16 (28) ◽  
pp. 14368-14377 ◽  
Author(s):  
Qiang Cui ◽  
Marcus Elstner
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Tight Binding ◽  
Empirical Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Semi Empirical

Semi-empirical (SE) methods are derived from Hartree–Fock (HF) or Density Functional Theory (DFT) by neglect and approximation of electronic integrals.

scholarly journals Analysis of the structural and electronic properties of 1-(5-Hydroxymethyl - 4 –[ 5 – (5-oxo-5-piperidin-1-yl-penta- 1,3dienyl)-benzo[1,3]dioxol-2-yl] -tetrahydro-furan-2-yl)-5- methyl-1H-pyrimidine-2,4dione molecule

2018 ◽  
Vol 33 (1) ◽  
pp. 71
Author(s):  
Ali Hashem Essa ◽  
A. F. Jalbout
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Ground State ◽  
Density Functional ◽  
Molecular Orbital Calculations ◽  
Active Molecule ◽  
Dft Methods ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical

The structural and electronic properties of 1-(5-Hydroxymethyl - 4 –[ 5 – (5-oxo-5-piperidin- 1 -yl-penta- 1,3 -dienyl)-benzo [1,3] dioxol- 2 -yl]- tetrahydro -furan-2 -yl)-5-methy l-1Hpyrimidine-2,4dione (AHE) molecule have been investigated theoretically by performing density functional theory (DFT), and semi empirical molecular orbital calculations. The geometry of the molecule is optimized at the level of Austin Model 1 (AM1), and the electronic properties and relative energies of the molecules have been calculated by density functional theory in the ground state. The resultant dipole moment of the AHE molecule is about 2.6 and 2.3 Debyes by AM1 and DFT methods respectively, This property of AHE makes it an active molecule with its environment, that is AHE molecule may interacts with its environment strongly in solution.

A DFT-D study of the interaction of methane, carbon monoxide, and nitrogen with cation-exchanged SAPO-34

2015 ◽  
Vol 230 (5) ◽  
Author(s):  
Michael Fischer ◽  
Robert G. Bell
Keyword(s):  
Density Functional Theory ◽  
Carbon Monoxide ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Dispersion Correction ◽  
Functional Theory ◽  
Guest Molecules ◽  
Semi Empirical ◽  
Methane Carbon

AbstractDensity-functional theory calculations including a semi-empirical dispersion correction (DFT-D) are employed to study the interaction of small guest molecules (CH

scholarly journals Computational Framework for a Systematic Investigation of Anionic Redox Process in Li-Rich Compounds

2019 ◽  
Author(s):  
Alexander Tygesen ◽  
Jinhyun Chang ◽  
Tejs Vegge ◽  
Juan Maria García Lastra
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Study ◽  
Systematic Investigation ◽  
Redox Processes ◽  
Oxygen Species ◽  
Computational Framework ◽  
Functional Theory ◽  
Redox Species ◽  
Formation And Evolution

Computational study of anionic redox processes in Li2MnO3, and newly developed methods for identifying and studying the evolution of anionic redox using density functional theory (DFT). A method for identifying localized anionic redox species is applied to a set of structures relaxed using the VASP software. A preconditioning scheme is presented to promote the formation of peroxo-like oxygen species, and study the formation and evolution of anionic redox.

scholarly journals Comparing Study of The Stability and spectral properties vibrations for some Tellurium (IV) compounds containing cycloctadienyl group by Quantum Mechanical Calculations

2013 ◽  
Vol 10 (3) ◽  
pp. 1041-1049
Author(s):  
Baghdad Science Journal
Keyword(s):  
Density Functional ◽  
Heat Of Formation ◽  
Basis Set ◽  
Orbital Energy ◽  
Empirical Methods ◽  
Geometrical Structures ◽  
Functional Theory ◽  
Exchange Correlation ◽  
The Stability ◽  
Semi Empirical

Density Functional Theory (DFT) with B3LYP hybrid exchange-correlation functional and 3-21G basis set and semi-empirical methods (PM3) were used to calculate the energies (total energy, binding energy (Eb), molecular orbital energy (EHOMO-ELUMO), heat of formation (?Hf)) and vibrational spectra for some Tellurium (IV) compounds containing cycloctadienyl group which can use as ligands with some transition metals or essential metals of periodic table at optimized geometrical structures.

A systematic investigation of acetylene activation and hydracyanation of the activated acetylene on Aun (n = 3–10) clusters via density functional theory

2016 ◽  
Vol 18 (20) ◽  
pp. 13830-13843 ◽  
Author(s):  
Seema Gautam ◽  
Abir De Sarkar
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Systematic Investigation ◽  
Functional Theory

Vinyl isocyanide formation: adsorption of C2H2 and HCN in succession on the Au9 cluster; towards polymerization: clustering of C2H2 on Au9.

scholarly journals Do Better Quality Embedding Potentials Accelerate the Convergence of QM/MM Models? The Case of Solvated Acid Clusters

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2466 ◽  
Author(s):  
Junming Ho ◽  
Yihan Shao ◽  
Jin Kato
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Water Model ◽  
Reaction Centre ◽  
Empirical Methods ◽  
Functional Theory ◽  
Highly Sensitive ◽  
Solvent Molecules ◽  
Dynamics Simulations ◽  
Semi Empirical

This study examines whether the use of more accurate embedding potentials improves the convergence of quantum mechanics/molecular mechanics (QM/MM) models with respect to the size of the QM region. In conjunction with density functional theory calculations using the ωB97X-D functional, various embedding potentials including the TIP3P water model, the effective fragment potential (EFP), and semi-empirical methods (PM6, PM7, and DFTB) were used to simulate the deprotonation energies of solvated acid clusters. The calculations were performed on solvated neutral (HA) and cationic (HB+) acids clusters containing 160 and 480 water molecules using configurations sampled from molecular dynamics simulations. Consistently, the ωB97X-D/EFP model performed the best when using a minimal QM region size. The performance for the other potentials appears to be highly sensitive to the charge character of the acid/base pair. Neutral acids display the expected trend that semi-empirical methods generally perform better than TIP3P; however, an opposite trend was observed for the cationic acids. Additionally, electronic embedding provided an improvement over mechanical embedding for the cationic systems, but not the neutral acids. For the best performing ωB97X-D/EFP model, a QM region containing about 6% of the total number of solvent molecules is needed to approach within 10 kJ mol−1 of the pure QM result if the QM region was chosen based on the distance from the reaction centre.

Calculations of the spin susceptibility and the electronic thermal effective mass of Be and Mg by spin density functional theory

1978 ◽  
Vol 56 (2) ◽  
pp. 266-279 ◽  
Author(s):  
L. Wilk ◽  
W. R. Fehlner ◽  
S. H. Vosko
Keyword(s):  
Density Functional Theory ◽  
Spin Density ◽  
Density Functional ◽  
Local Spin Density Approximation ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Plane Wave Method ◽  
Effective Masses ◽  
Experimental Values ◽  
Semi Empirical

The spin-density functional theory was used to calculate the electronic thermal effective masses (including electron–electron interactions) and the spin susceptibilities (via a variational principle) for beryllium and magnesium. The necessary exchange-correlation functionals were treated in the local-spin-density approximation. The single-particle electron states were calculated by the augmented-plane-wave method using a self-consistent muffin-tin potential. It was found that the calculated thermal effective masses agreed very well with semi-empirical results from fits to the Fermi surface. We conclude that the accepted values of the electron–phonon mass enhancement parameter λep are too large by approximately 50%. The theoretical spin susceptibiltiy for Be was found to be 0.47 × 10−6 (cgs volume units), in marked disagreement with the experimental values. For Mg we obtained the value 1.65 × 10−6 (cgs volume units).

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