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On the curvature in logarithmic plots of rate coefficients for chemical reactions
In terms of the reduced potential energy barrier ζ = Δu(TS)/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e(-ζ). The coupling between vibrational modes of the medium to the reaction coordinate leads to a proportionality of the regularized gamma function of...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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BioMed Central
2011
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3117758/ https://www.ncbi.nlm.nih.gov/pubmed/21545752 http://dx.doi.org/10.1186/1752-153X-5-22 |
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author | Canepa, Carlo |
author_facet | Canepa, Carlo |
author_sort | Canepa, Carlo |
collection | PubMed |
description | In terms of the reduced potential energy barrier ζ = Δu(TS)/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e(-ζ). The coupling between vibrational modes of the medium to the reaction coordinate leads to a proportionality of the regularized gamma function of Euler Q(a,ζ) = Γ(a,ζ)/Γ(a), with a being the number of modes coupled to the reaction coordinate. In this work, the experimental rate coefficients at various temperatures for several chemical reactions were fitted to the theoretical expression in terms of Q(a,ζ) to determine the extent of its validity and generality. The new expression affords lower deviations from the experimental points in 29 cases out of 38 and it accounts for the curvature in the logarithmic plots of rate coefficients versus inverse temperature. In the absence of tunneling, conventional theories predict the curvature of these plots to be identically zero. |
format | Online Article Text |
id | pubmed-3117758 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2011 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-31177582011-06-18 On the curvature in logarithmic plots of rate coefficients for chemical reactions Canepa, Carlo Chem Cent J Research Article In terms of the reduced potential energy barrier ζ = Δu(TS)/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e(-ζ). The coupling between vibrational modes of the medium to the reaction coordinate leads to a proportionality of the regularized gamma function of Euler Q(a,ζ) = Γ(a,ζ)/Γ(a), with a being the number of modes coupled to the reaction coordinate. In this work, the experimental rate coefficients at various temperatures for several chemical reactions were fitted to the theoretical expression in terms of Q(a,ζ) to determine the extent of its validity and generality. The new expression affords lower deviations from the experimental points in 29 cases out of 38 and it accounts for the curvature in the logarithmic plots of rate coefficients versus inverse temperature. In the absence of tunneling, conventional theories predict the curvature of these plots to be identically zero. BioMed Central 2011-05-06 /pmc/articles/PMC3117758/ /pubmed/21545752 http://dx.doi.org/10.1186/1752-153X-5-22 Text en Copyright ©2011 Canepa et al |
spellingShingle | Research Article Canepa, Carlo On the curvature in logarithmic plots of rate coefficients for chemical reactions |
title | On the curvature in logarithmic plots of rate coefficients for chemical reactions |
title_full | On the curvature in logarithmic plots of rate coefficients for chemical reactions |
title_fullStr | On the curvature in logarithmic plots of rate coefficients for chemical reactions |
title_full_unstemmed | On the curvature in logarithmic plots of rate coefficients for chemical reactions |
title_short | On the curvature in logarithmic plots of rate coefficients for chemical reactions |
title_sort | on the curvature in logarithmic plots of rate coefficients for chemical reactions |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3117758/ https://www.ncbi.nlm.nih.gov/pubmed/21545752 http://dx.doi.org/10.1186/1752-153X-5-22 |
work_keys_str_mv | AT canepacarlo onthecurvatureinlogarithmicplotsofratecoefficientsforchemicalreactions |