Theoretical studies on heats of formation for polynitrocubanes using the density functional theory B3LYP method and semiempirical MO methods

2001 ◽  
Vol 14 (8) ◽  
pp. 583-588 ◽  
Author(s):  
Ji Zhang ◽  
Heming Xiao ◽  
Xuedong Gong
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Heats Of Formation ◽  
Theoretical Studies ◽  
Functional Theory ◽  
B3lyp Method ◽  
The Density Functional Theory

Ab Initio Theoretical Studies of Relative Stabilities and IR Spectrum of 5-Methylcytosine Tautomers

2003 ◽  
Vol 2003 (4) ◽  
pp. 195-199 ◽  
Author(s):  
Lida Ghassemzadeh ◽  
Majid Monajjemi ◽  
Karim Zare
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Relative Energy ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Relative Stabilities ◽  
B3lyp Method ◽  
Wide Range ◽  
Good Agreement

The structure and relative energies of the tautomers of 5-methylcytosine in the gasphase and in different solvents are predicted using MP2 and density functional theory methods. The order of stability for these tautomers is C3>C1>C2>C4>C5>C6 calculated by MP2 and C1>C3>C2>C4>C5>C6 calculated by the B3LYP method. Relative energy calculations are performed in wide range of solvent dielectrics and in all solvents the oxo-amino C1 is predicted as the most stable tautomer. The infrared spectra of two dominant tautomers are calculated in the gas phase using HF and density functional theory. Good agreement between calculated (DFT) and experimental harmonic vibrational frequencies is found.

scholarly journals Theoretical Studies of Acrolein Hydrogenation to Propenol and Propanal on Au3 and Au5

2016 ◽  
Author(s):  
Guo-Jun Kang ◽  
Shuai He ◽  
Xue-Feng Ren
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Gold Clusters ◽  
The Other ◽  
Model Systems ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Supported Gold

The stepwise hydrogenation of the C=C bond and C=O group of acrolein on Au3 and Au5 model systems is investigated using the density functional theory(DFT) PW91 functional. Our results show that the C=C hydrogenation is more favorable than that of C=O bond on Au3 with the barriers of the rate-determining step being 0.35 and 0.62 eV respectively. On the other hand, the C=O reduction is preferred over the hydrogenation of the C=C bond on Au5. The corresponding barriers of the rate-determining steps are 0.45 and 0.54 eV, respectively. This demonstrated that the second hydrogenation step controls the reaction on both Au3 and Au5 for C=O and C=C hydrogenation and the C=O hydrogenation on Au5 is preferred over the hydrogenation of the C=C bond, which is helpful to address the reactivity of small size-selected supported gold clusters.

scholarly journals Single-Atom X/g-C3N4(X = Au1, Pd1, and Ru1) Catalysts for Acetylene Hydrochlorination: A Density Functional Theory Study

Catalysts ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 808 ◽  
Author(s):  
Zhou ◽  
Zhu ◽  
Kang
Keyword(s):  
Density Functional Theory ◽  
Energy Barrier ◽  
Density Functional ◽  
Single Atom ◽  
Functional Theory ◽  
Acetylene Hydrochlorination ◽  
B3lyp Method ◽  
The Density Functional Theory ◽  
Catalytic Mechanisms ◽  
Functional Dispersion

The mechanisms of the single-atom X/g-C3N4(X = Au1, Pd1, and Ru1) catalysts for the acetylene hydrochlorination reaction were systematically investigated using the density functional theory (DFT) B3LYP method. The density functional dispersion correction obtained by the DFT-D3 method was taken into account. During the reaction, C2H2 and HCl were well activated and the analysis of the adsorption energy demonstrated the adsorption performance of C2H2 is better than that of HCl. The catalytic mechanisms of the three catalysts consist of one intermediate and two transition states. Moreover, our results showed that the three single-atom catalysts improve the catalytic activity of the reaction to different degrees. The calculated energy barrier declines in the order of Pd1/g-C3N4 > Ru1/g-C3N4 > Au1/g-C3N4, and the energy barrier for the Au1/g-C3N4 catalyst was only 13.66 kcal/mol, proving that single-atom Au1/g-C3N4 may be a potential catalyst for hydrochlorination of acetylene to vinyl chloride.

scholarly journals Theoretical Studies of Some Fluoro Compounds with Silicon, Phosphorus and Sulphur and Establishment of Negative Hyperconjugation through Calculation of Charge

2008 ◽  
Vol 5 (1) ◽  
pp. 136-143
Author(s):  
P. K. Mohamed Imran ◽  
K. Subramani
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Anomeric Effect ◽  
Theoretical Studies ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Inductive Effects ◽  
Negative Hyperconjugation ◽  
Electronegative Atom ◽  
Bond Character

Hyperconjugation is an act to build π bond character into bonds that have only σ character. Negative Hyperconjugation is the flow or movements of electrons from π to σ* orbitals and more particularly from π orbital of a carbon atom to the σ* orbital of the C—X bond, where X is any electronegative atom. This effect is different from Inductive effects. An attempt is made to study the negative hyperconjugation (Anomeric Effect) by the calculation of the charges at the Density Functional Theory (DFT) level for some compounds with hypervalent atoms like Si, P & S

scholarly journals Synthesis, characterization and computational studies of 2-cyano-6-methoxybenzothiazole as a firefly-luciferin precursor

2018 ◽  
Vol 24 (5) ◽  
pp. 255-258
Author(s):  
Ghasem Shahmoradi ◽  
Saeid Amani
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Basis Set ◽  
Computational Studies ◽  
Stable Conformation ◽  
Functional Theory ◽  
Novel Approach ◽  
B3lyp Method ◽  
The Density Functional Theory ◽  
Firefly Luciferin

Abstract A novel approach to the synthesis of 2-cyano-6-methoxybenzothiazole via the Cu-catalyzed cyanation of 2-iodo-6-methoxybenzothiazole was developed. K4[Fe(CN)6] was used as a source of cyanide, and a Cu/N,N,N′,N′-tetramethylethylenediamine (TMEDA) system was utilized as a catalyst. This approach is scalable and can be practiced with operational benign. The most stable conformation of 2-cyano-6-methoxybenzothiazole was delineated using the density functional theory (DFT)/B3LYP method with 6-311++G(d, p) basis set.

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