| Overtone-induced dissociation and isomerization dynamics of the hydroxymethyl radical (CH(2)OH and CD(2)OH). I. A theoretical study. | |
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MedLine Citation:
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PMID: 22380039 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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The dissociation of the hydroxymethyl radical, CH(2)OH, and its isotopolog, CD(2)OH, following the excitation of high OH stretch overtones is studied by quasi-classical molecular dynamics calculations using a global potential energy surface (PES) fitted to ab initio calculations. The PES includes CH(2)OH and CH(3)O minima, dissociation products, and all relevant barriers. Its analysis shows that the transition states for OH bond fission and isomerization are both very close in energy to the excited vibrational levels reached in recent experiments and involve significant geometry changes relative to the CH(2)OH equilibrium structure. The energies of key stationary points are refined using high-level electronic structure calculations. Vibrational energies and wavefunctions are computed by coupled anharmonic vibrational calculations. They show that high OH-stretch overtones are mixed with other modes. Consequently, trajectory calculations carried out at energies about ∼3000 cm(-1) above the barriers reveal that despite initial excitation of the OH stretch, the direct OH bond fission is relatively slow (10 ps) and a considerable fraction of the radicals undergoes isomerization to the methoxy radical. The computed dissociation energies are: D(0)(CH(2)OH → CH(2)O + H) = 10 188 cm(-1), D(0)(CD(2)OH → CD(2)O + H) = 10 167 cm(-1), D(0)(CD(2)OH → CHDO + D) = 10 787 cm(-1). All are in excellent agreement with the experimental results. For CH(2)OH, the barriers for the direct OH bond fission and isomerization are: 14 205 and 13 839 cm(-1), respectively. |
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Authors:
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E Kamarchik; C Rodrigo; J M Bowman; H Reisler; A I Krylov |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: The Journal of chemical physics Volume: 136 ISSN: 1089-7690 ISO Abbreviation: J Chem Phys Publication Date: 2012 Feb |
Date Detail:
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Created Date: 2012-03-02 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0375360 Medline TA: J Chem Phys Country: United States |
Other Details:
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Languages: eng Pagination: 084304 Citation Subset: IM |
Affiliation:
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Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, USA. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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