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.

1.
L.
Vereecken
,
B.
Aumont
,
I.
Barnes
,
J. W.
Bozzelli
,
M. J.
Goldman
,
W. H.
Green
,
S.
Madronich
,
M. R.
McGillen
,
A.
Mellouki
,
J. J.
Orlando
 et al, “
Perspective on mechanism development and structure-activity relationships for gas-phase atmospheric chemistry
,”
Int. J. Chem. Kinet.
50
,
435
469
(
2018
).
2.
M. F.
Shaw
,
B.
Sztáray
,
L. K.
Whalley
,
D. E.
Heard
,
D. B.
Millet
,
M. J.
Jordan
,
D. L.
Osborn
, and
S. H.
Kable
, “
Photo-tautomerization of acetaldehyde as a photochemical source of formic acid in the troposphere
,”
Nat. Commun.
9
,
2584
(
2018
).
3.
A. T.
Archibald
,
M. R.
McGillen
,
C. A.
Taatjes
,
C. J.
Percival
, and
D. E.
Shallcross
, “
Atmospheric transformation of enols: A potential secondary source of carboxylic acids in the urban troposphere
,”
Geophys. Res. Lett.
34
,
L21801
, (
2007
).
4.
D. U.
Andrews
,
B. R.
Heazlewood
,
A. T.
Maccarone
,
T.
Conroy
,
R. J.
Payne
,
M. J. T.
Jordan
, and
S. H.
Kable
, “
Photo-tautomerization of acetaldehyde to vinyl alcohol: A potential route to tropospheric acids
,”
Science
337
,
1203
1206
(
2012
).
5.
A. E.
Clubb
,
M. J. T.
Jordan
,
S. H.
Kable
, and
D. L.
Osborn
, “
Phototautomerization of acetaldehyde to vinyl alcohol: A primary process in UV-irradiated acetaldehyde from 295 to 335 nm
,”
J. Phys. Chem. Lett.
3
,
3522
3526
(
2012
).
6.
Y.
Miller
and
R. B.
Gerber
, “
Dynamics of vibrational overtone excitations of H2SO4, H2SO4-H2O: Hydrogen-hopping and photodissociation processes
,”
J. Am. Chem. Soc.
128
,
9594
9595
(
2006
).
7.
T.
Nagy
,
J.
Yosa Reyes
, and
M.
Meuwly
, “
Multisurface adiabatic reactive molecular dynamics
,”
J. Chem. Theory Comput.
10
,
1366
1375
(
2014
).
8.
J.
Yosa Reyes
,
T.
Nagy
, and
M.
Meuwly
, “
Competitive reaction pathways in vibrationally induced photodissociation of H2SO4
,”
Phys. Chem. Chem. Phys.
16
,
18533
18544
(
2014
).
9.
J. Y.
Reyes
,
S.
Brickel
,
O. T.
Unke
,
T.
Nagy
, and
M.
Meuwly
, “
HSO3Cl: A prototype molecule for studying OH-stretching overtone induced photodissociation
,”
Phys. Chem. Chem. Phys.
18
,
6780
6788
(
2016
).
10.
V.
Vaida
,
H. G.
Kjaergaard
,
P. E.
Hintze
, and
D. J.
Donaldson
, “
Photolysis of sulfuric acid vapor by visible solar radiation
,”
Science
299
,
1566
1568
(
2003
).
11.
J.
Zhong
,
H.
Li
,
M.
Kumar
,
J.
Liu
,
L.
Liu
,
X.
Zhang
,
X. C.
Zeng
, and
J. S.
Francisco
, “
Mechanistic insight into the reaction of organic acids with SO3 at the air-water interface
,”
Angew. Chem., Int. Ed.
58
,
8351
8355
(
2019
).
12.
K.
Farah
,
F.
Müller-Plathe
, and
M. C.
Böhm
, “
Classical reactive molecular dynamics implementations: State of the art
,”
ChemPhysChem
13
,
1127
1151
(
2012
).
13.
M.
Meuwly
, “
Reactive molecular dynamics: From small molecules to proteins
,”
Wiley Interdiscip. Rev.: Comput. Mol. Sci.
9
,
e1386
(
2019
).
14.
W. S.
McCulloch
and
W.
Pitts
, “
A logical calculus of the ideas immanent in nervous activity
,”
Bull. Sci. Math.
5
,
115
133
(
1943
).
15.
F.
Rosenblatt
, “
The perceptron: A probabilistic model for information storage and organization in the brain
,”
Psychol. Rev.
65
,
386
408
(
1958
).
16.
J.
Behler
, “
Neural network potential-energy surfaces in chemistry: A tool for large-scale simulations
,”
Phys. Chem. Chem. Phys.
13
,
17930
17955
(
2011
).
17.
R. J.
Schalkoff
,
Artificial Neural Networks
(
McGraw-Hill
,
New York
,
1997
), Vol. 1.
18.
K.
Hornik
,
M.
Stinchcombe
, and
H.
White
, “
Multilayer feedforward networks are universal approximators
,”
Neural Network
2
,
359
366
(
1989
).
19.
B. J.
Finlayson-Pitts
and
J. N.
Pitts
, Jr.
,
Chemistry of the Upper and Lower Atmosphere: Theory, Experiments, and Applications
(
Elsevier
,
1999
).
20.
D. B.
Millet
,
M.
Baasandorj
,
D. K.
Farmer
,
J. A.
Thornton
,
K.
Baumann
,
P.
Brophy
,
S.
Chaliyakunnel
,
J. A.
de Gouw
,
M.
Graus
,
L.
Hu
 et al, “
A large and ubiquitous source of atmospheric formic acid
,”
Atmos. Chem. Phys.
15
,
6283
6304
(
2015
).
21.
S.
So
,
U.
Wille
, and
G.
da Silva
, “
Atmospheric chemistry of enols: A theoretical study of the vinyl alcohol + OH + O2 reaction mechanism
,”
Environ. Sci. Technol.
48
,
6694
6701
(
2014
).
22.
B. C.
Shepler
,
B. J.
Braams
, and
J. M.
Bowman
, “
Quasiclassical trajectory calculations of acetaldehyde dissociation on a global potential energy surface indicate significant non-transition state dynamics
,”
J. Phys. Chem. A
111
,
8282
8285
(
2007
).
23.
Y.-C.
Han
,
B. C.
Shepler
, and
J. M.
Bowman
, “
Quasiclassical trajectory calculations of the dissociation dynamics of CH3CHO at high energy yield many products
,”
J. Phys. Chem. Lett.
2
,
1715
1719
(
2011
).
24.
B. J.
Braams
and
J. M.
Bowman
, “
Permutationally invariant potential energy surfaces in high dimensionality
,”
Int. Rev. Phys. Chem.
28
,
577
606
(
2009
).
25.
J.
Peeters
,
V. S.
Nguyen
, and
J.-F.
Müller
, “
Atmospheric vinyl alcohol to acetaldehyde tautomerization revisited
,”
J. Phys. Chem. Lett.
6
,
4005
4011
(
2015
).
26.
O. T.
Unke
,
S.
Brickel
, and
M.
Meuwly
, “
Sampling reactive regions in phase space by following the minimum dynamic path
,”
J. Chem. Phys.
150
,
074107
(
2019
).
27.
A. H.
Larsen
,
J. J.
Mortensen
,
J.
Blomqvist
,
I. E.
Castelli
,
R.
Christensen
,
M.
Dułak
,
J.
Friis
,
M. N.
Groves
,
B.
Hammer
,
C.
Hargus
 et al, “
The atomic simulation environment—A Python library for working with atoms
,”
J. Phys.: Condens. Matter
29
,
273002
(
2017
).
28.
O. T.
Unke
and
M.
Meuwly
, “
PhysNet: A neural network for predicting energies, forces, dipole moments, and partial charges
,”
J. Chem. Theory Comput.
15
,
3678
3693
(
2019
).
29.
J.
Behler
and
M.
Parrinello
, “
Generalized neural-network representation of high-dimensional potential-energy surfaces
,”
Phys. Rev. Lett.
98
,
146401
(
2007
).
30.
O. T.
Unke
and
M.
Meuwly
, “
A reactive, scalable, and transferable model for molecular energies from a neural network approach based on local information
,”
J. Chem. Phys.
148
,
241708
(
2018
).
31.
J.
Gilmer
,
S. S.
Schoenholz
,
P. F.
Riley
,
O.
Vinyals
, and
G. E.
Dahl
, “
Neural message passing for quantum chemistry
,” in
Proceedings of the 34th International Conference on Machine Learning
(
Journal of Machine Learning Research
,
2017
), Vol. 70, pp.
1263
1272
.
32.
S.
Grimme
,
J.
Antony
,
S.
Ehrlich
, and
H.
Krieg
, “
A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu
,”
J. Chem. Phys.
132
,
154104
(
2010
).
33.
S.
Grimme
,
S.
Ehrlich
, and
L.
Goerigk
, “
Effect of the damping function in dispersion corrected density functional theory
,”
J. Comput. Chem.
32
,
1456
1465
(
2011
).
34.
A. G.
Baydin
,
B. A.
Pearlmutter
,
A. A.
Radul
, and
J. M.
Siskind
, “
Automatic differentiation in machine learning: A survey
,”
J. Mach. Learn. Res.
18
,
1
43
(
2018
).
35.
C.
Møller
and
M. S.
Plesset
, “
Note on an approximation treatment for many-electron systems
,”
Phys. Rev.
46
,
618
622
(
1934
).
36.
T. H.
Dunning
, Jr.
, “
Gaussian basis sets for use in correlated molecular calculations. I. The atoms boron through neon and hydrogen
,”
J. Chem. Phys.
90
,
1007
1023
(
1989
).
37.
H.-J.
Werner
,
P. J.
Knowles
,
G.
Knizia
,
F. R.
Manby
,
M.
Schütz
,
P.
Celani
,
W.
Györffy
,
D.
Kats
,
T.
Korona
,
R.
Lindh
 et al, MOLPRO, version 2018.2, a package of ab initio programs,
2018
.
38.
B.
Huang
and
O. A.
von Lilienfeld
, “
The “DN” of chemistry: Scalable quantum machine learning with “amons
,” arXiv:1707.04146 (
2017
).
39.
J. J. P.
Stewart
, “
Optimization of parameters for semiempirical methods V: Modification of NDDO approximations and application to 70 elements
,”
J. Mol. Model.
13
,
1173
1213
(
2007
).
40.
J. J. P.
Stewart
, SCC MOPAC 2016,
Colorado Springs
,
CO, USA
,
2016
.
41.
G. M.
Torrie
and
J. P.
Valleau
, “
Nonphysical sampling distributions in Monte Carlo free-energy estimation: Umbrella sampling
,”
J. Comput. Phys.
23
,
187
199
(
1977
).
42.
J.
Behler
, “
Perspective: Machine learning potentials for atomistic simulations
,”
J. Chem. Phys.
145
,
170901
(
2016
).
43.
J.
Behler
, “
Constructing high-dimensional neural network potentials: A tutorial review
,”
Int. J. Quantum Chem.
115
,
1032
1050
(
2015
).
44.
J. S.
Smith
,
O.
Isayev
, and
A. E.
Roitberg
, “
ANI-1: An extensible neural network potential with DFT accuracy at force field computational cost
,”
Chem. Sci.
8
,
3192
3203
(
2017
).
45.
U.
Rivero
,
O. T.
Unke
,
M.
Meuwly
, and
S.
Willitsch
, “
Reactive atomistic simulations of Diels-Alder reactions: The importance of molecular rotations
,”
J. Chem. Phys.
151
,
104301
(
2019
).
46.
L.
Verlet
, “
Computer “Experiments” on classical fluids. I. Thermodynamical properties of Lennard-Jones molecules
,”
Phys. Rev.
159
,
98
103
(
1967
).
47.
T. J.
Lee
and
P. R.
Taylor
, “
A diagnostic for determining the quality of single-reference electron correlation methods
,”
Int. J. Quantum Chem.
36
,
199
207
(
1989
).
48.
Q.
Ma
and
H.-J.
Werner
, “
Explicitly correlated local coupled-cluster methods using pair natural orbitals
,”
Wiley Interdiscip. Rev.: Comput. Mol. Sci.
8
,
e1371
(
2018
).
49.
C.
Bannwarth
,
S.
Ehlert
, and
S.
Grimme
, “
GFN2-xTB—An accurate and broadly parametrized self-consistent tight-binding quantum chemical method with multipole electrostatics and density-dependent dispersion contributions
,”
J. Chem. Theory Comput.
15
,
1652
1671
(
2019
).
50.
Y.
Paukku
,
K. R.
Yang
,
Z.
Varga
, and
D. G.
Truhlar
, “
Global ab initio ground-state potential energy surface of N4
,”
J. Chem. Phys.
139
,
044309
(
2013
).
51.
J.
Huang
,
M.
Buchowiecki
,
T.
Nagy
,
J.
Vaníček
, and
M.
Meuwly
, “
Kinetic isotope effect in malonaldehyde determined from path integral Monte Carlo simulations
,”
Phys. Chem. Chem. Phys.
16
,
204
211
(
2014
).
52.
K.
Karandashev
,
Z.-H.
Xu
,
M.
Meuwly
,
J.
Vaníček
, and
J. O.
Richardson
, “
Kinetic isotope effects and how to describe them
,”
Struct. Dyn.
4
,
061501
(
2017
).
53.
Y.
Kurosaki
and
K.
Yokoyama
, “
Photodissociation of acetaldehyde, CH3CHO → CH3+ HCO: Direct ab initio molecular dynamics study
,”
Chem. Phys. Lett.
371
,
568
575
(
2003
).
54.
Y.
Kurosaki
and
K.
Yokoyama
, “
Photodissociation of acetaldehyde, CH3CHO → CH4+ CO: Direct ab initio dynamics study
,”
J. Phys. Chem. A
106
,
11415
11421
(
2002
).
55.
Y.
Kurosaki
, “
Photodissociation of acetaldehyde, CH3CHO → CH4+ CO: II. Direct ab initio molecular dynamics study
,”
Chem. Phys. Lett.
421
,
549
553
(
2006
).
56.
A. W.
Harrison
,
A.
Kharazmi
,
M. F.
Shaw
,
M. S.
Quinn
,
K. L. K.
Lee
,
K.
Nauta
,
K. N.
Rowell
,
M. J. T.
Jordan
, and
S. H.
Kable
, “
Dynamics and quantum yields of H2+ CH2CO as a primary photolysis channel in CH3CHO
,”
Phys. Chem. Chem. Phys.
21
,
14284
14295
(
2019
).
57.
L. B.
Harding
,
Y.
Georgievskii
, and
S. J.
Klippenstein
, “
Roaming radical kinetics in the decomposition of acetaldehyde
,”
J. Phys. Chem. A
114
,
765
777
(
2010
).
58.
J. R.
Barker
, “
Multiple-Well, multiple-path unimolecular reaction systems. I. MultiWell computer program suite
,”
Int. J. Chem. Kinet.
33
,
232
245
(
2001
).
59.
B. F.
Gherman
,
R. A.
Friesner
,
T.-H.
Wong
,
Z.
Min
, and
R.
Bersohn
, “
Photodissociation of acetaldehyde: The CH4+ CO channel
,”
J. Chem. Phys.
114
,
6128
6133
(
2001
).
60.
H.
Tachikawa
and
N.
Ohta
, “
Photodissociation mechanism of acetaldehyde. RRK and RRKM study
,”
Chem. Phys. Lett.
224
,
465
469
(
1994
).
61.
J.
Yosa
and
M.
Meuwly
, “
Vibrationally induced dissociation of sulfuric acid (H2SO4)
,”
J. Phys. Chem. A
115
,
14350
14360
(
2011
).

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