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Transition state

About: Transition state is a research topic. Over the lifetime, 4978 publications have been published within this topic receiving 117965 citations. The topic is also known as: transition state of elementary reaction.


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Journal ArticleDOI
TL;DR: In this article, the C2H5• + O2 reaction has been examined in detail via highly sophisticated electronic structure methods, including the geometries, energies, and harmonic vibrational frequencies of the reactants, transition states, intermediates, and products.
Abstract: The C2H5• + O2 reaction, central to ethane oxidation and thus of fundamental importance to hydrocarbon combustion chemistry, has been examined in detail via highly sophisticated electronic structure methods. The geometries, energies, and harmonic vibrational frequencies of the reactants, transition states, intermediates, and products for the reaction of the ethyl radical (X 2A‘) with O2 (X 3 , a 1Δg) have been investigated using the CCSD and CCSD(T) ab initio methods with basis sets ranging in quality from double-zeta plus polarization (DZP) to triple-zeta plus double polarization with f functions (TZ2Pf). Five mechanisms (M1−M5) involving the ground-state reactants are introduced within the context of previous experimental and theoretical studies. In this work, each mechanism is systematically explored, giving the following overall 0 K activation energies with respect to ground-state reactants, Ea(0 K), at our best level of theory: (M1) direct hydrogen abstraction from the ethyl radical by O2 to give e...

480 citations

Journal ArticleDOI
TL;DR: A Bayesian formula relating the equilibrium and transition-path ensembles to identify transition states, rank reaction coordinates, and estimate rate coefficients is used and a variational procedure to optimize reaction coordinates is introduced.
Abstract: The molecular mechanism of a reaction in solution is reflected in its transition-state ensemble and transition paths. We use a Bayesian formula relating the equilibrium and transition-path ensembles to identify transition states, rank reaction coordinates, and estimate rate coefficients. We also introduce a variational procedure to optimize reaction coordinates. The theory is illustrated with applications to protein folding and the dipole reorientation of an ordered water chain inside a carbon nanotube. To describe the folding of a simple model of a three-helix bundle protein, we variationally optimize the weights of a projection onto the matrix of native and nonnative amino acid contacts. The resulting one-dimensional reaction coordinate captures the folding transition state, with formation and packing of helix 2 and 3 constituting the bottleneck for folding.

470 citations

Journal ArticleDOI
TL;DR: In this paper, an algorithm is presented for determining multi-dimensional reaction coordinates between two known conformers, which is suitable for the study of complex isomerization reactions, including allosteric transitions in proteins and more general conformational changes of macromolecules.

456 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the complementary of experimental studies and computer simulations or quantum chemical calculations performed on the water exchange reaction between coordination shells around metal ions in aqueous solution.

445 citations

Journal ArticleDOI
TL;DR: It is argued that even more useful than identifying the rate-determining step is identifying the Rate-controlling transition states and the rate -controlling intermediates, the species whose energetics must be most accurately measured or calculated to achieve an accurate kinetic model for any reaction mechanism.
Abstract: For many decades, the concept of a “rate-determining step” has been of central importance in understanding chemical kinetics in multistep reaction mechanisms and using that understanding to advantage. Yet a rigorous method for identifying the rate-determining step in a reaction mechanism was only recently introduced, via the “degree of rate control” of elementary steps. By extending that idea, we argue that even more useful than identifying the rate-determining step is identifying the rate-controlling transition states and the rate-controlling intermediates. These identify a few distinct chemical species whose relative energies we could adjust to achieve a faster or slower net reaction rate. Their relative energies could be adjusted by a variety of practical approaches, such as adding or modifying a catalyst, modifying the solvent, or simply modifying a reactant’s molecular structure to affect electronic or steric control on the relative energies of the key species. Since these key species are the ones wh...

438 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202364
2022136
2021148
2020155
2019145
2018147