Isomerization and decomposition reactions of acetaldehyde relevant to atmospheric processes from dynamics simulations on neural network-based potential energy surfaces
Acetaldehyde (AA) isomerization [to vinylalcohol (VA)] and decomposition (into either CO + CH4 or H2 + 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 ∼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 ∼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.
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
2020 |
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| Erschienen: |
2020 |
| Enthalten in: |
Zur Gesamtaufnahme - volume:152 |
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| Enthalten in: |
The Journal of chemical physics - 152(2020), 21 vom: 07. Juni, Seite 214304 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Käser, Silvan [VerfasserIn] |
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| Anmerkungen: |
Date Revised 07.06.2020 published: Print Citation Status PubMed-not-MEDLINE |
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| doi: |
10.1063/5.0008223 |
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| funding: |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM310846692 |
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| 100 | 1 | |a Käser, Silvan |e verfasserin |4 aut | |
| 245 | 1 | 0 | |a Isomerization and decomposition reactions of acetaldehyde relevant to atmospheric processes from dynamics simulations on neural network-based potential energy surfaces |
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| 500 | |a Date Revised 07.06.2020 | ||
| 500 | |a published: Print | ||
| 500 | |a Citation Status PubMed-not-MEDLINE | ||
| 520 | |a Acetaldehyde (AA) isomerization [to vinylalcohol (VA)] and decomposition (into either CO + CH4 or H2 + 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 ∼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 ∼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 | ||
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| 700 | 1 | |a Meuwly, Markus |e verfasserin |4 aut | |
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