The location of stationary points in the reaction of fluoroformyloxyl radical (FCO2(C2V)) with atomic hydrogen: A computational study on the pathways of the singlet and triplet reaction and intersystem crossing

2013 ◽  
Vol 1022 ◽  
pp. 86-93 ◽  
Author(s):  
Esmail Vessally ◽  
Sattar Ebrahimi ◽  
Moein Goodarzi ◽  
Abdolvahab Seif
Keyword(s):  
Atomic Hydrogen ◽  
Computational Study ◽  
Stationary Points ◽  
Intersystem Crossing

Ultrafast Intersystem Crossing in 1-Nitronaphthalene. An Experimental and Computational Study

2008 ◽  
Vol 112 (3) ◽  
pp. 358-365 ◽  
Author(s):  
Jimena S. Zugazagoitia ◽  
César Xavier Almora-Díaz ◽  
Jorge Peon
Keyword(s):  
Computational Study ◽  
Intersystem Crossing

The Impact of Twisting on the Intersystem Crossing in Acenes: An Experimental and Computational Study

2022 ◽  
Author(s):  
Partha Malakar ◽  
Veniamin Borin ◽  
Anjan Bedi ◽  
Igor Schapiro ◽  
Ori Gidron ◽  
...  
Keyword(s):  
Excited State ◽  
Electronic Properties ◽  
Light Harvesting ◽  
Computational Study ◽  
Dominant Role ◽  
Intersystem Crossing ◽  
Side Group ◽  
Excited State Dynamics ◽  
Optical And Electronic Properties ◽  
The Impact

Due to their unique excited state dynamics, acenes play a dominant role in optoelectronic and light-harvesting applications. Their optical and electronic properties are typically tailored by side-group engineering, which often...

Computational study on the reaction of atomic chlorine with 1,2-dibromoethane (CH2BrCH2Br)

2013 ◽  
Vol 91 (11) ◽  
pp. 1123-1129 ◽  
Author(s):  
Ang-yang Yu
Keyword(s):  
Transition State ◽  
Rate Constants ◽  
Transition State Theory ◽  
Computational Study ◽  
Minimum Energy ◽  
State Theory ◽  
Basis Set ◽  
Stationary Points ◽  
Variational Transition State Theory ◽  
Variational Transition State

In this work, the reaction mechanism and kinetics of Cl + CH2BrCH2Br → products are theoretically investigated for the first time. The optimized geometries and frequencies of all of the stationary points and selected points along the minimum-energy path for the three hydrogen abstraction channels and two bromine abstraction channels are calculated at the BH&H-LYP level with the 6-311G** basis set and the energy profiles are further calculated at the CCSD(T) level of theory. The rate constants are evaluated using the conventional transition-state theory, the canonical variational transition-state theory, and the canonical variational transition-state theory with a small-curvature tunneling correction over the temperature range 200–1000 K. The results show that reaction channel 3 is the primary channel and the calculated rate constants are in good agreement with available experimental values. The three-parameter Arrhenius expression for the total rate constants over 200–1000 K is provided.

MECHANISMS FOR THE DECOMPOSITION OF HYDROXYL-RADICAL-INDUCED CYTOSINE HYDROPEROXIDES: A COMPUTATIONAL STUDY

2013 ◽  
Vol 12 (04) ◽  
pp. 1350027 ◽  
Author(s):  
ZE-QIN CHEN ◽  
YING XUE
Keyword(s):  
Hydroxyl Radical ◽  
Computational Study ◽  
Chemical Properties ◽  
Basis Set ◽  
Stationary Points ◽  
Decomposition Products ◽  
Natural Processes ◽  
Full Optimization ◽  
Explicit Water ◽  
First Time

Hydroxyl-radical-induced damage to cytosine leads to a multitude of base modifications, which contribute to the natural processes of aging, mutagenesis and carcinogenesis. The stable products resulting from the main hydroxyl-radical-induced cytosine hydroperoxide, 5-hydroxy-6-hydroperoxyl-5,6-dihydrocytosine (5-OH-6-OOH-DHC), have been mapped out in the present work for the first time using ab initio calculations. Optimized geometries of all stationary structures in the gas phase were determined at the MP2 and B3LYP using the 6-31G(d) basis set and at the B3LYP/6-311++G(d,p) levels of theory. Energies were also determined at the G3MP2 level of theory. Meanwhile, full optimization of all stationary points were also performed in aqueous solution at the B3LYP/CPCM/6-31G(d) level of theory to evaluate the solvent effect. Three distinct possible pathways, pathways A–C, were evaluated. For pathway C, four channels, channels D–G, were characterized in turn. In each pathway, both the direct and the water-mediated processes were considered. The calculated results clearly manifest that (i) pathway C is kinetically favored over pathways A and B and is the most energetically feasible decomposition process of 5-OH-6-OOH-DHC; (ii) for pathway C, channels D, E and G are energetically feasible mechanisms and 6,7-dihydroxy-[1,3,5]triazepane-2,4-dione, 1-carbamoyl-2-oxo-4,5-dihydroxyimidazolidine, and biuret therefore are predicted to be the kinetically favored decomposition products of 5-OH-6-OOH-DHC; (iii) channel G may be kinetically favored over channels D and E and have the highest possibility to occur; (iv) the thermal decomposition of 5-OH-6-OOH-DHC can be significantly promoted by the presence of one explicit water molecule. Apart from characterizing the experimental products well, the main striking result of the present DFT computational study is the identification of a new theoretical optimum decomposition product, i.e. 6,7-dihydroxy-[1,3,5]triazepane-2,4-dione. The data and insights presented here have elucidated the chemical properties of 5-OH-6-OOH-DHC in free radical reactions and should facilitate to assess their mutagenic features.

scholarly journals A combined experimental and computational study on the reaction dynamics of the 1-propynyl radical (CH3CC; X2A1) with ethylene (H2CCH2; X1A1g) and the formation of 1-penten-3-yne (CH2CHCCCH3; X1A′)

2019 ◽  
Vol 21 (40) ◽  
pp. 22308-22319 ◽  
Author(s):  
Chao He ◽  
Long Zhao ◽  
Aaron M. Thomas ◽  
Galiya R. Galimova ◽  
Alexander M. Mebel ◽  
...  
Keyword(s):  
Atomic Hydrogen ◽  
Mass Velocity ◽  
Computational Study ◽  
Center Of Mass ◽  
Reaction Dynamics ◽  
Contour Maps

Center-of-mass velocity flux contour maps for the reactions of 1-propynyl with ethylene for the atomic hydrogen loss leading to 1-penten-3-yne.

scholarly journals Computational Study of Inversion-topomerization Pathways in 1,3-Dimethylcyclohexane and 1,4-Dimethylcyclohexane: Ab Initio Conformational Analysis

2020 ◽  
Author(s):  
Huiting Bian ◽  
Yifan Zhang ◽  
Yongjin Wang ◽  
Jun Zhao ◽  
Xiaohui Ruan ◽  
...  
Keyword(s):  
Potential Energy ◽  
Conformational Analysis ◽  
Potential Energy Surfaces ◽  
Computational Study ◽  
Three Dimensional ◽  
Boltzmann Distribution ◽  
Molecular Structures ◽  
Stationary Points ◽  
Energy Surfaces ◽  
Cis And Trans

This work concerns the typical conformational behaviors for di-substituted cyclohexanes that inherently depend on spatial orientations of side chains in flexible cyclic ring. The 1,3-dimethylcyclohexane and 1,4-dimethylcyclohexane in both cis- and trans-configurations were focused here to unravel their conformational inversion-topomerization mechanisms. Full geometry optimizations were performed at B3LYP/6-311++G(d,p) level of theory to explicitly identify all distinguishable molecular structures, and thus explore potential energy surfaces (PES) of the complete interconversion routes for two stereoisomers of 1,3-dimethylcyclohexane and 1,4-dimethylcyclohexane. Additional quantum calculations were carried out by separately applying MP2/6-311++G(d,p), G4, and CCSD(T)/6-311++G(d,p) methods to further refine all PES’ stationary points. With respect to quantum results, the conformational analysis was conducted to gain insight into the determination, thermodynamic stabilities, and relative energies of distinct molecular geometric structures. On base of highly biased conformational equilibria, the temperature-dependent populations of stable local minima for four studied dimethylcyclohexanes were obtained by utilizing Boltzmann distribution within 300-2500 K. Moreover, two unique interconversion processes for them, including inversion and topomerization, were fully investigated, and their potential energy surfaces were illustrated with the rigorous descriptions in two or three-dimensional schemes for clarify.

Formation of a pre-reaction hydrogen-bonded complex and its significance in the potential energy surface of the OH + SO2→ HOSO2 reaction: A computational study

2017 ◽  
Vol 16 (05) ◽  
pp. 1750046 ◽  
Author(s):  
Vijay M. Miriyala ◽  
Priya Bhasi ◽  
Zanele P. Nhlabatsi ◽  
Sanyasi Sitha
Keyword(s):  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Computational Study ◽  
Stationary Points ◽  
Second Step ◽  
Computational Calculations ◽  
Reaction Complex ◽  
Hydrogen Bonded

Using computational calculations, we have revisited the potential energy surface (PES) of the reaction between OH and SO2, which is believed as the rate-limiting step in the atmospheric formation of H2SO4. In this work, we report for the first time the presence of a pre-reaction hydrogen-bonded complex between OH and SO2 in the reaction PES. Based on this finding, it has been shown that the reaction can be considered as a two-step process in which the first step is the formation of the pre-reaction complex and the second step is the transformation of this complex to the product. It was observed that due to the presence of this pre-reaction complex as a potential well in the reaction PES, the barrier height got increased by around two-fold for the second step. Based on this observation, it has been proposed that the kinetics of the reaction is going to be affected. Also based on the analysis of the geometries of this pre-reaction complex and the transition state, it has been argued that the step involving the transformation of this pre-reaction complex to the product via the transition state is going to be the slowest step as this transformation involves large structural changes of the stationary points involved.

scholarly journals A computational study of the reactions of atomic hydrogen with fluoromethanes: kinetics and product channels

1997 ◽  
Vol 269 (1-2) ◽  
pp. 107-116 ◽  
Author(s):  
R.J. Berry ◽  
C.J. Ehlers ◽  
D.R. Burgess ◽  
M.R. Zachariah ◽  
P. Marshall
Keyword(s):  
Atomic Hydrogen ◽  
Computational Study
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