A DFT study of thymine and its tautomers

2009 ◽  
Vol 87 (2) ◽  
pp. 406-415 ◽  
Author(s):  
Dongsheng Jiao ◽  
Hongyan Wang ◽  
Yanlan Zhang ◽  
Yu Tang
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Ionization Potential ◽  
Density Functional ◽  
The Other ◽  
Basis Sets ◽  
Electron Affinities ◽  
Proton Affinities ◽  
Functional Theory ◽  
Theoretical Results

The structures and the relative energies of six possible tautomers of the thymine base have been studied by density functional theory (DFT) using the B3LYP and BP86 functionals. The keto-thymine (T1) is predicted to be the most stable thymine tautomer, which is consistent with the other theoretical results and experimental data. The corresponding thymine cations and anions are studied using the same level of theory with double-ζ plus polarization and diffuse functions (DZP++) basis sets. The ionization potentials (IPs), the electron affinities (EAs), and proton affinities (PAs) for different protonation sites in thymine base are obtained. T1 has the largest ionization potential and the lowest proton affinity among all the considered thymine tautomers.

scholarly journals Predicting the new carbon nanocages, fullerynes: a DFT study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Qasemnazhand ◽  
Farhad Khoeini ◽  
Farah Marsusi
Keyword(s):  
Density Functional Theory ◽  
Lithium Ion Batteries ◽  
Density Functional ◽  
Lithium Ion ◽  
The Other ◽  
Electron Affinities ◽  
Chemical Formula ◽  
Functional Theory ◽  
Triple Bonds ◽  
Structural And Electronic Properties

AbstractIn this study, based on density functional theory, we propose a new branch of pseudo-fullerenes which contain triple bonds with sp hybridization. We call these new nanostructures fullerynes, according to IUPAC. We present four samples with the chemical formula of C4nHn, and the structures derived from fulleranes. We compare the structural and electronic properties of these structures with those of two common fullerenes and fulleranes systems. The calculated electron affinities of the sampled fullerynes are negative, and much smaller than those of fullerenes, so they should be chemically more stable than fullerenes. Although fulleranes also exhibit higher chemical stability than fullerynes, but pentagon or hexagon of the fullerane structures cannot pass ions and molecules. Applications of fullerynes can be included in the storage of ions and gases at the nanoscale. On the other hand, they can also be used as cathode/anode electrodes in lithium-ion batteries.

Calculation of Ionization Potential and Electron Affinity of the Optoelectronic Material Iridium (III) Metal Complexes Containing the 2-phenyl Pyridine-Type Ligands

2013 ◽  
Vol 738 ◽  
pp. 52-55
Author(s):  
Hong Ying Xia ◽  
Guo Hua Ge ◽  
Feng Zhao
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Metal Complexes ◽  
Ionization Potential ◽  
Transition Metal Complexes ◽  
Electron Affinity ◽  
Density Functional ◽  
Electron Affinities ◽  
Functional Theory ◽  
Experimental Values

Solid state ionization potential and electron affinity of iridium (III) metal complexes containing the 2-phenyl pyridine-type ligands was calculated using density functional theory (DFT). It is shown that the calculated results are in well agreement with the experimental values. With this approach, it is convince to obtain solid state ionization potentials and electron affinities of a range of neutral transition metal complexes.

Calculation of the second electron affinities of atoms

1990 ◽  
Vol 68 (9) ◽  
pp. 1585-1589 ◽  
Author(s):  
Yufei Guo ◽  
M. A. Whitehead
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Correlation Energy ◽  
Energy Functional ◽  
The Self ◽  
Electron Affinities ◽  
Functional Theory ◽  
Sphere Radius ◽  
Generalized Exchange

The second electron affinities of the atoms helium to krypton are calculated using the self-interaction corrected generalized exchange local-spin-density functional theory with the correlation energy functional. The dependence of the second electron affinities of the elements O, S, and Se on the Watson sphere radius is discussed. The present results are compared with other theoretical values and experimental data for the elements helium through krypton. Keywords: second electron affinity, density functional theory.

scholarly journals Computational studies of the thermodynamic properties, and global and reactivity descriptors of fluorescein dye derivatives in acetonitrile using density functional theory

2021 ◽  
pp. 174751982199451
Author(s):  
Juma Mzume Juma ◽  
Said AH Vuai
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ionization Potential ◽  
Molecular Orbital ◽  
Density Functional ◽  
Energy Gap ◽  
Basis Sets ◽  
Hybrid Functional ◽  
Functional Theory ◽  
Reactivity Descriptors

This work reports density functional theory calculations of the optimized geometries, molecular reactivity, energy gap, and thermodynamic properties of molecular dyes fluorescein (FS), fluorescein attached with methoxy (FSO), fluorescein attached with amine (FSA), fluorescein attached with methane (FSM), fluorescein attached with ethene (FSE), and fluorescein attached with thiophene (FST) using the hybrid functional B3LYP and 6-311G basis sets. When donating groups are attached to the molecular dye, the bond lengths are slightly decreased which is important for easy transfer of electron from donating to the accepting group. For all dyes, highest occupied molecular orbital/lowest occupied molecular orbital analysis results in positive outcomes upon electron injection to semiconductors and subsequent dye regeneration by the electrolyte. The ionization potential increases with increasing conjugation; therefore, the molecular dye attached to thiophene has the highest ionization potential. Meanwhile, a donating group with increased conjugation results in low electron affinity.

scholarly journals Theoretical study of the adsorption of benzene on coinage metals

2014 ◽  
Vol 10 ◽  
pp. 1775-1784 ◽  
Author(s):  
Werner Reckien ◽  
Melanie Eggers ◽  
Thomas Bredow
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Study ◽  
Dispersion Correction ◽  
Functional Theory ◽  
Coinage Metals ◽  
Adsorption Energies ◽  
Theoretical Results ◽  
Good Agreement

The adsorption of benzene on the M(111), M(100) and M(110) surfaces of the coinage metals copper (M = Cu), silver (M = Ag) and gold (M = Au) is studied on the basis of density functional theory (DFT) calculations with an empirical dispersion correction (D3). Variants of the Perdew–Burke–Ernzerhof functionals (PBE, RPBE and RevPBE) in combination with different versions of the dispersion correction (D3 and D3(BJ)) are compared. PBE-D3, PBE-D3(BJ) and RPBE-D3 give similar results which exhibit a good agreement with experimental data. RevPBE-D3 and RevPBE-D3(BJ) tend to overestimate adsorption energies. The inclusion of three-center terms (PBE-D3(ABC)) leads to a slightly better agreement with the experiment in most cases. Vertical adsorbate–substrate distances are calculated and compared to previous theoretical results. The observed trends for the surfaces and metals are consistent with the calculated adsorption energies.

scholarly journals A Quantum Chemistry Approach to the Force Fields of the Asymmetrical Thionyl Halides FS(O)Cl, CF3S(O)F and CF3S(O)Cl

2011 ◽  
Vol 66 (5) ◽  
pp. 499-504
Author(s):  
Angelina del C. Coronel ◽  
Myriam E. Gargiulo ◽  
Eduardo L. Varetti ◽  
Lis E. Fernández
Keyword(s):  
Experimental Data ◽  
Density Functional Theory ◽  
Quantum Mechanics ◽  
Density Functional ◽  
Force Fields ◽  
Internal Force ◽  
Vibrational Properties ◽  
Functional Theory ◽  
Definition Of ◽  
Theoretical Results

The vibrational properties of the asymmetrical thionyl halides FS(O)Cl, CF3S(O)F and CF3S(O)Cl were studied by means of density functional theory (DFT) techniques. The available experimental data and assignments for these molecules were compared with the theoretical results and revised. These data were subsequently used in the definition of the corresponding scaled quantum mechanics (SQM) force fields. A set of internal force constants was also calculated from such force fields

Benchmark of Simplified Time-Dependent Density Functional Theory for UV-Vis Spectral Properties of Porphyrinoids

2019 ◽  
Author(s):  
Kamal Batra ◽  
Stefan Zahn ◽  
Thomas Heine
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Absolute Error ◽  
Time Dependent ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Framework Materials ◽  
Dependent Density

<p>We thoroughly benchmark time-dependent density- functional theory for the predictive calculation of UV/Vis spectra of porphyrin derivatives. With the aim to provide an approach that is computationally feasible for large-scale applications such as biological systems or molecular framework materials, albeit performing with high accuracy for the Q-bands, we compare the results given by various computational protocols, including basis sets, density-functionals (including gradient corrected local functionals, hybrids, double hybrids and range-separated functionals), and various variants of time-dependent density-functional theory, including the simplified Tamm-Dancoff approximation. An excellent choice for these calculations is the range-separated functional CAM-B3LYP in combination with the simplified Tamm-Dancoff approximation and a basis set of double-ζ quality def2-SVP (mean absolute error [MAE] of ~0.05 eV). This is not surpassed by more expensive approaches, not even by double hybrid functionals, and solely systematic excitation energy scaling slightly improves the results (MAE ~0.04 eV). </p>

scholarly journals Computational Study of the Electron Spectra of Vapor-Phase Indole and Four Azaindoles

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1947
Author(s):  
Delano P. Chong
Keyword(s):  
Density Functional Theory ◽  
Vapor Phase ◽  
Density Functional ◽  
Computational Study ◽  
Geometry Optimization ◽  
The Other ◽  
Functional Theory ◽  
Electron Spectra

After geometry optimization, the electron spectra of indole and four azaindoles are calculated by density functional theory. Available experimental photoemission and excitation data for indole and 7-azaindole are used to compare with the theoretical values. The results for the other azaindoles are presented as predictions to help the interpretation of experimental spectra when they become available.

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