Nonlocal density functional theory as a practical tool in calculations on transition states and activation energies. Applications to elementary reaction steps in organic chemistry

1992 ◽  
Vol 114 (27) ◽  
pp. 10890-10897 ◽  
Author(s):  
Liangyou Fan ◽  
Tom Ziegler
Keyword(s):  
Organic Chemistry ◽  
Density Functional Theory ◽  
Density Functional ◽  
Transition States ◽  
Activation Energies ◽  
Elementary Reaction ◽  
Functional Theory ◽  
Practical Tool

THE H2NO POTENTIAL ENERGY SURFACE EXPLORED WITH HIGH LEVEL AB INITIO AND DENSITY FUNCTIONAL THEORY METHODS

2007 ◽  
Vol 06 (03) ◽  
pp. 549-562
Author(s):  
ABRAHAM F. JALBOUT
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Functional ◽  
Energy Surface ◽  
Hybrid Methods ◽  
Transition States ◽  
Basis Set ◽  
Functional Theory ◽  
High Level

The transition states for the H 2 NO decomposition and rearrangements mechanisms have been explored by the CBS-Q method or by density functional theory. Six transition states were located on the potential energy surface, which were explored with the Quadratic Complete Basis Set (CBS-Q) and Becke's one-parameter density functional hybrid methods. Interesting deviations between the CBS-Q results and the B1LYP density functional theory lead us to believe that further study into this system is necessary. In the efforts to further assess the stabilities of the transition states, bond order calculations were performed to measure the strength of the bonds in the transition state.

scholarly journals Density Functional Theory Based Micro- and Macro-Kinetic Studies of Ni-Catalyzed Methanol Steam Reforming

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 349 ◽  
Author(s):  
Changming Ke ◽  
Zijing Lin
Keyword(s):  
Density Functional Theory ◽  
Steam Reforming ◽  
Density Functional ◽  
Reaction Pathway ◽  
Elementary Reaction ◽  
Main Reaction ◽  
Methanol Steam Reforming ◽  
Surface Species ◽  
Functional Theory ◽  
Microkinetic Model

The intrinsic mechanism of Ni-catalyzed methanol steam reforming (MSR) is examined by considering 54 elementary reaction steps involved in MSR over Ni(111). Density functional theory computations and transition state theory analyses are performed on the elementary reaction network. A microkinetic model is constructed by combining the quantum chemical results with a continuous stirring tank reactor model. MSR rates deduced from the microkinetic model agree with the available experimental data. The microkinetic model is used to identify the main reaction pathway, the rate determining step, and the coverages of surface species. An analytical expression of MSR rate is derived based on the dominant reaction pathway and the coverages of surface species. The analytical rate equation is easy to use and should be very helpful for the design and optimization of the operating conditions of MSR.

Mechanistic insight into Cu/Ag-cocatalyzed C–H activation of arenes with oxygen as the terminal oxidant

RSC Advances ◽  
2016 ◽  
Vol 6 (42) ◽  
pp. 35855-35858 ◽  
Author(s):  
Gui-Yu Ruan ◽  
Zheng-Hang Qi ◽  
Ye Zhang ◽  
Wei Liu ◽  
Yong Wang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Transition States ◽  
Functional Theory ◽  
Mechanistic Insight ◽  
Insight Into

The possible transition states of C–H activation on the dehydrogenate coupling of arenes with alcohols employing Ag(i) additives were investigated using B3LYP density functional theory.

scholarly journals Mechanism of Reactions of 1-Substituted Silatranes and Germatranes, 2,2-Disubstituted Silocanes and Germocanes, 1,1,1-Trisubstituted Hyposilatranes and Hypogermatranes with Alcohols (Methanol, Ethanol): DFT Study

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2803 ◽  
Author(s):  
Denis Chachkov ◽  
Rezeda Ismagilova ◽  
Yana Vereshchagina
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Activation Energies ◽  
Functional Theory ◽  
Gibbs Energies ◽  
The Density Functional Theory ◽  
Lower Activation ◽  
One Step ◽  
Intramolecular Hydrogen

The mechanism of reactions of silatranes and germatranes, and their bicyclic and monocyclic analogues with one molecule of methanol or ethanol, was studied at the Density Functional Theory (DFT) B3PW91/6-311++G(df,p) level of theory. Reactions of 1-substituted sil(germ)atranes, 2,2-disubstituted sil(germ)ocanes, and 1,1,1-trisubstituted hyposil(germ)atranes with alcohol (methanol, ethanol) proceed in one step through four-center transition states followed by the opening of a silicon or germanium skeleton and the formation of products. According to quantum chemical calculations, the activation energies and Gibbs energies of activation of reactions with methanol and ethanol are close, their values decrease in the series of atranes–ocanes–hypoatranes for interactions with both methanol and ethanol. The reactions of germanium-containing derivatives are characterized by lower activation energies in comparison with the reactions of corresponding silicon-containing compounds. The annular configurations of the product molecules with electronegative substituents are stabilized by the transannular N→X (X = Si, Ge) bond and different intramolecular hydrogen contacts with the participation of heteroatoms of substituents at the silicon or germanium.

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