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Isomerization and decomposition reactions of acetaldehyde relevant to atmospheric processes from dynamics simulations on neural network-based potential energy surfaces

Kaser, Silvan and Unke, Oliver T. and Meuwly, Markus. (2020) Isomerization and decomposition reactions of acetaldehyde relevant to atmospheric processes from dynamics simulations on neural network-based potential energy surfaces. Journal of Chemical Physics, 152 (21). p. 1.

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Official URL: https://edoc.unibas.ch/80560/

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Abstract

Acetaldehyde (AA) isomerization [to vinylalcohol (VA)] and decomposition (into either CO + CH4 or H-2 + C2H2O) are studied using a fully dimensional, reactive potential energy surface represented as a neural network (NN). The NN, trained on 432 399 reference structures from MP2/aug-cc-pVTZ calculations, has a mean absolute error of 0.0453 kcal/mol and a root mean squared error of 1.186 kcal mol(-1) for a test set of 27 399 structures. For the isomerization process AA -> VA, the minimum dynamical path implies that the C-H vibration and the C-C-H (with H being the transferring H-atom) and the C-C-O angles are involved to surmount the 68.2 kcal/mol barrier. Using an excess energy of 93.6 kcal/mol-the typical energy available in the solar spectrum and sufficient to excite to the first electronically excited state-to initialize the molecular dynamics, no isomerization to VA is observed on the 500 ns time scale. Only with excess energies of similar to 127.6 kcal/mol (including the zero point energy of the AA molecule), isomerization occurs on the nanosecond time scale. Given that collisional quenching times under tropospheric conditions are similar to 1 ns, it is concluded that formation of VA following photoexcitation of AA from actinic photons is unlikely. This also limits the relevance of this reaction pathway to be a source for formic acid.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Physikalische Chemie (Meuwly)
UniBasel Contributors:Meuwly, Markus
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:AIP Publishing
ISSN:0021-9606
e-ISSN:1089-7690
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:16 Mar 2021 10:40
Deposited On:16 Mar 2021 10:40

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