Document Detail

QCT and QM calculations of the Cl(2P) + NH3 reaction: influence of the reactant well on the dynamics.
MedLine Citation:
PMID:  22388701     Owner:  NLM     Status:  PubMed-not-MEDLINE    
A detailed dynamics study, using both quasi-classical trajectory (QCT) and reduced-dimensional quantum mechanical (QM) calculations, was carried out to understand the reactivity and mechanism of the Cl((2)P) + NH(3)→ HCl + NH(2) gas-phase reaction, which evolves through deep wells in the entry and exit channels. The calculations were performed on an analytical potential energy surface recently developed by our group, PES-2010 [M. Monge-Palacios, C. Rangel, J. C. Corchado and J. Espinosa-Garcia, Int. J. Quantum. Chem., 2011], together with a simplified model surface, mod-PES, in which the reactant well is removed to analyze its influence. The main finding was that the QCT and QM methods show a change of the reaction probability with collision energy, suggesting a change of the atomic-level mechanism of reaction with energy. This change disappeared when the mod-PES was used, showing that the behaviour at low energies is a direct consequence of the existence of the reactant well. Analysis of the trajectories showed that different mechanisms operate depending on the collision energy. Thus, while at high energies (E(coll) > 5 kcal mol(-1)) practically all trajectories are direct, at low energies (E(coll) < 3 kcal mol(-1)) the trajectories are indirect, i.e., with the mediation of a trapping complex in the entry and/or the exit wells. The reactant complex allows repeated encounters between the reactants, increasing the reaction probability at low energies. The differential cross section results reinforce this change of mechanism, showing also the influence of the reactant well on this reaction. Thus, the PES-2010 surface yields a forward-backward symmetry in the scattering, while when the reactant well is removed with the mod-PES the shape is more isotropic.
M Monge-Palacios; M Yang; J Espinosa-García
Publication Detail:
Type:  Comment; Journal Article     Date:  2012-03-05
Journal Detail:
Title:  Physical chemistry chemical physics : PCCP     Volume:  14     ISSN:  1463-9084     ISO Abbreviation:  Phys Chem Chem Phys     Publication Date:  2012 Apr 
Date Detail:
Created Date:  2012-03-15     Completed Date:  2012-07-09     Revised Date:  2013-03-21    
Medline Journal Info:
Nlm Unique ID:  100888160     Medline TA:  Phys Chem Chem Phys     Country:  England    
Other Details:
Languages:  eng     Pagination:  4824-34     Citation Subset:  -    
Departamento de Química Física, Universidad de Extremadura, 06071 Badajoz, Spain.
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MeSH Terms
Comment On:
2012 Dec 28;14(48): 16792
Erratum In:
Phys Chem Chem Phys. 2012 dec 28;16792-3

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