Development of chemical kinetics models from atomistic reactive molecular dynamics simulations: application to iso-octane combustion and rubber ablative degradation

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dc.contributor.author Sasikumar, Kiran
dc.contributor.author Ranganathan, Raghavan
dc.contributor.author Rokkam, Srujan
dc.contributor.author Desai, Tapan
dc.contributor.author Burnes, Richard
dc.contributor.author Cross, Peter
dc.coverage.spatial United States of America
dc.date.accessioned 2022-06-04T07:39:51Z
dc.date.available 2022-06-04T07:39:51Z
dc.date.issued 2022-05
dc.identifier.citation Sasikumar, Kiran; Ranganathan, Raghavan; Rokkam, Srujan; Desai, Tapan; Burnes, Richard and Cross, Peter, "Development of chemical kinetics models from atomistic reactive molecular dynamics simulations: application to iso-octane combustion and rubber ablative degradation", The Journal of Physical Chemistry A, DOI: 10.1021/acs.jpca.2c00901, May 2022. en_US
dc.identifier.issn 1089-5639
dc.identifier.issn 1520-5215
dc.identifier.uri https://doi.org/10.1021/acs.jpca.2c00901
dc.identifier.uri https://repository.iitgn.ac.in/handle/123456789/7783
dc.description.abstract Modeling the complex chemical phenomena resulting from multiple active species and long-chain polymers is limited by uncertainties in the reaction rate parameters, which increase rapidly with the number of active species and/or reaction pathways. Reactive molecular dynamics simulations have the potential to help obtain in-depth information on the chemical reactions that occur between the polymer (e.g., ablative material) and the multiple active species in an aggressive environment. In this work, we demonstrate that molecular dynamics (MD) simulations using the ReaxFF interatomic potential can be used to obtain the reaction kinetics of complex reaction pathways at high temperatures. We report two recently developed tools, namely, MolfrACT and KinACT, designed to extract chemical kinetic pathways by postprocessing reactive MD simulation data. The pathway extraction is based on a new algorithm, Consistent Reaction Stoichiometry via an Iterative Scheme (CReSIS), for the automated extraction of reactions and kinetics from MD trajectories. As a validation of the methodology, we first report the kinetic analysis and mechanisms for the high-temperature combustion of iso-octane. The observed reaction pathways are consistent with experimental models. In addition, we compare the activation energies of select iso-octane combustion pathways with experimental data and show that nanosecond timescale molecular dynamics simulations are sufficient to obtain realistic estimates of activation energies for different fuel consumption reaction pathways at high temperatures. The framework developed here can potentially be combined with time-series forecasting and machine learning methods to further reduce the computational complexity of transient molecular dynamics simulations, yet yielding realistic chemical kinetics information. Subsequently, the CReSIS scheme applied to ethylene–propylene–diene–monomer (EPDM) rubber ablative reveals that H2O, C2H4, and HCHO are the major products during the initial stages of the polymer degradation in high-temperature oxidative environments. While prior work involving ReaxFF simulations is restricted to overall rates of formation of any species, we extract kinetic information for individual reaction pathways. In this paper, we present several reaction pathways observed during the EPDM rubber degradation into the dominant products and report the pathway-specific reaction rates. Arrhenius analysis reveals that the dominant reaction pathway activation energies for the formation of water, ethylene, and formaldehyde are 34.42, 27.26, and 6.37 kcal/mol, respectively. In contrast, the activation energies for the overall formation (across all reaction pathways) of these products are in the 40–50 kcal/mol range.
dc.description.statementofresponsibility by Kiran Sasikumar, Raghavan Ranganathan, Srujan Rokkam, Tapan Desai, Richard Burnes and Peter Cross
dc.language.iso en_US en_US
dc.publisher American Chemical Society en_US
dc.subject Molecular dynamics (MD) en_US
dc.subject Long-chain polymers en_US
dc.subject (CReSIS) en_US
dc.subject EPDM en_US
dc.subject Kinetic information en_US
dc.title Development of chemical kinetics models from atomistic reactive molecular dynamics simulations: application to iso-octane combustion and rubber ablative degradation en_US
dc.type Article en_US
dc.relation.journal The Journal of Physical Chemistry A


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