Atomistic insight into the effects of electrostatic fields on hydrocarbon reaction kinetics
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Published version
Author(s)
Kritikos, Efstratios
Lele, Aditya
van Duin, Adri CT
Giusti, Andrea
Type
Journal Article
Abstract
Reactive Molecular Dynamics (MD) and Density Functional Theory (DFT) computations are performed to provide insight into the effects of external electrostatic fields on hydrocarbon reaction kinetics. By comparing the results from MD and DFT, the suitability of the MD method in modeling electrodynamics is first assessed. Results show that the electric field-induced polarization predicted by the MD charge equilibration method is in good agreement with various DFT charge partitioning schemes. Then, the effects of oriented external electric fields on the transition pathways of non-redox reactions are investigated. Results on the minimum energy path suggest that electric fields can cause catalysis or inhibition of oxidation reactions, whereas pyrolysis reactions are not affected due to the weaker electronegativity of the hydrogen and carbon atoms. MD simulations of isolated reactions show that the reaction kinetics is also affected by applied external Lorentz forces and interatomic Coulomb forces since they can increase or decrease the energy of collision depending on the molecular conformation. In addition, electric fields can affect the kinetics of polar species and force them to align in the direction of field lines. These effects are attributed to energy transfer via intermolecular collisions and stabilization under the external Lorentz force. The kinetics of apolar species is not significantly affected mainly due to the weak induced dipole moment even under strong electric fields. The dynamics and reaction rates of species are studied by means of large-scale combustion simulations of n-dodecane and oxygen mixtures. Results show that under strong electric fields, the fuel, oxidizer, and most product molecules experience translational and rotational acceleration mainly due to close charge transfer along with a reduction in their vibrational energy due to stabilization. This study will serve as a basis to improve the current methods used in MD and to develop novel methodologies for the modeling of macroscale reacting flows under external electrostatic fields.
Date Issued
2023-02-03
Date Acceptance
2023-01-03
Citation
The Journal of Chemical Physics, 2023, 158 (5), pp.1-18
ISSN
0021-9606
Publisher
AIP Publishing
Start Page
1
End Page
18
Journal / Book Title
The Journal of Chemical Physics
Volume
158
Issue
5
Copyright Statement
© 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license
(http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0134785
(http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0134785
License URL
Identifier
https://aip.scitation.org/doi/10.1063/5.0134785
Publication Status
Published
Date Publish Online
2023-01-05