Dynamic Modeling of Reaction Pathways on the Gibbs Energy Surface

2000 ◽  
Vol 39 (2) ◽  
pp. 508-517 ◽  
Author(s):  
Srinivas R. Vuddagiri ◽  
Kenneth R. Hall ◽  
Philip T. Eubank
Keyword(s):  
Gibbs Energy ◽  
Dynamic Modeling ◽  
Energy Surface ◽  
Reaction Pathways

scholarly journals Thermodynamic Stabilities of U(VI) Minerals: Estimated and Observed Relationships

1996 ◽  
Vol 465 ◽  
Author(s):  
Robert J. Finch
Keyword(s):  
Gibbs Energy ◽  
Reaction Pathways ◽  
Free Energies ◽  
Fine Grained ◽  
Surface Energies ◽  
Stability Diagrams ◽  
Activity Diagrams ◽  
Mineral Stability ◽  
Mineral Compositions

ABSTRACTGibbs free energies of formation (ΔG°ƒ) for several structurally related U(VI) minerals are estimated by summing the Gibbs energy contributions from component oxides. The estimated ΔG°f values are used to construct activity-activity (stability) diagrams, and the predicted stability fields are compared with observed mineral occurrences and reaction pathways. With some exceptions, natural occurrences agree well with the mineral stability fields estimated for the systems Sio2-Cao-Uo3-UOH2O and Co2-caO-UO3-H2O providing confidence in the estimated thermodynamic values. Activity-activity diagrams are sensitive to small differences in ΔG°f values, and mineral compositions must be known accurately, including structurally bound H2O. The estimated ΔG°f values are not considered reliable for a few minerals for two major reasons: (1) the structures of the minerals in question are not closely similar to those used to estimate the ΔG°f* values of the component oxides, and/or (2) the minerals in question are exceptionally fine grained, leading to large surface energies that increase the effective mineral solubilities.

scholarly journals A theoretical study on the mechanism of the reaction between azacyclopropenylidene and oxirane

2015 ◽  
Vol 80 (1) ◽  
pp. 53-62
Author(s):  
Ying Jing ◽  
Xiaojun Tan
Keyword(s):  
Energy Surface ◽  
Theoretical Study ◽  
Single Point ◽  
Geometry Optimization ◽  
Vibrational Analysis ◽  
Membered Ring ◽  
Reaction Pathways ◽  
Stationary Points ◽  
Energy Property ◽  
Mechanism Of The Reaction

The reaction mechanism between azacyclopropenylidene and oxirane has been systematically investigated employing the second-order M?ller-Plesset perturbation theory (MP2) method to better understand the azacyclopropenylidene reactivity with three-membered ring compound oxirane. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are also further corrected by CCSD(T)/6-311+G* single-point calculations. Our calculational results show that there are two possible reaction pathways. From the kinetic viewpoint, the first pathway is primary. From the viewpoint of thermodynamics, the second is dominating.

Density Functional Study of the Reaction Pathways of the Decomposition of Azidoborane: A Curtius-type Rearrangement

2021 ◽  
Vol 25 (12) ◽  
pp. 98-106
Author(s):  
Renu Parashar ◽  
Sunita Bansal
Keyword(s):  
Density Functional ◽  
Energy Surface ◽  
Nitrogen Loss ◽  
Reaction Pathways ◽  
Functional Study ◽  
Energy Minimum ◽  
Density Functional Study ◽  
First Order ◽  
One Step ◽  
The One

Density functional study is used for the decomposition of azidoborane and the possibility of borylnitrene being an intermediate in the formation of iminoborane both in the singlet and triplet state. Our calculations has shown that in the one step concerted manner, both singlet and triplet azidoborane can lead to the formation of iminoborane. A two step path (nitrogen loss followed by isomerization of borylnitrene) is a first order saddle point on the energy surface. However, such a two step process is possible for the triplet azidoborane, since triplet borylnitrene corresponds to a energy minimum on the potential energy surface.

Quantum modeling of the reaction between ozone and hydrogen cyanide

2017 ◽  
Vol 16 (07) ◽  
pp. 1750063
Author(s):  
Kahina Sidi Said ◽  
Madjid Nait Achour
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Thermodynamic Stability ◽  
Hydrogen Cyanide ◽  
Energy Surface ◽  
Topological Analysis ◽  
Reaction Pathways ◽  
Intrinsic Reaction Coordinate ◽  
Singlet Potential Energy Surface ◽  
Quantum Modeling

This work consists of an investigation, using current methods of quantum chemistry and, at first, on the basis of the available experimental results, about the new mechanisms of the reaction between ozone and hydrogen cyanide (HCN) in gaseous phases. Three possible reaction pathways which we have determined as the most probable and, all three, leading exactly to the same products, are proposed here. For each of these pathways, several steps for which we performed a kinetic study were identified in the singlet potential energy surface. To confirm the proposed mechanisms, we have achieved a study including the intrinsic reaction coordinate (IRC), the topological analysis of atoms in molecule and the harmonic vibrational frequencies calculations. The obtained results reveal that the final products have considerable thermodynamic stability and this reaction is exothermic in standard conditions.

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