Stephen Klippenstein

Stephen J. Klippenstein

Argonne Distinguished Fellow (Theoretical Chemistry)

Biography

  • B.Sc. (1983) Mathematics and Chemistry (Honours), University of British Columbia, Canada
  • Ph.D. (1988) Physical Chemistry, California Institute of Technology
    • Thesis Title: Theoretical Studies of Chemical Reaction Dynamics
    • Advisor: Prof. R. A. Marcus
  • Postdoc (1988) with Rudy Marcus, California Institute of Technology                    
  • Postdoc (1988,1989) with Casey Hynes, University of Colorado, Boulder              
  • Assistant, Associate, Full Professor (1989-2000) Department of Chemistry, Case Western Reserve University                 
  • Principal Member of the Technical Staff (2000-2005) Combustion Research Facility, Sandia National Laboratories, Livermore
  • Senior Chemist (2005-2013) Chemical Sciences and Engineering, Argonne
  • Distinguished Fellow (2013-) Chemical Sciences and Engineering, Argonne

E-mail: sjk@​anl.​gov

Research Interests: Our work aims to develop detailed electronic/atomistic/molecular level pictures that accurately describing the kinetics and dynamics of complex chemical reactions. Our studies typically involve some combination of electronic structure calculations, transition state theory, trajectory simulations, and master equation modeling. We apply these methods to interesting problems in combustion, interstellar, and atmospheric chemistry. Through substantive comparisons with state-of-the-art experiments we explore the foundations of chemical kinetics. A long term goal, that is now coming to fruition, involve the fully in silico development of global chemical models.

Recent Publications

Theoretically Informed Kinetics (ThInK): Establishing a Modern C0-C3 Mechanism for Combustion Modeling, S. J. Klippenstein, R. Sivaramakrishnan, D. H. Bross, M. P. Burke, S. N. Elliott, P. Glarborg, C. F. Goldsmith, N. Hansen, A. W. Jasper, N. J. Labbe, C. R. Mulvihill, B. Ruscic, Y. Tao, J. Zador, J. A. Miller, Combust. Flame, submitted (2025).

Modeling Combustion Chemistry using C3MechV4.0: An Extension to Mixtures of Hydrogen, Ammonia, Alkanes, and Cycloalkanes, L. Pratali Maffei, R. Langer, Y. Murakami, S. W. Wagnon, P. Wang, J. Liu, M. Raza, Y. Zhu, S. Girhe, C. Schwenzer, J. Beeckmann, S. J. Klippenstein, T. Faravelli, H. Pitsch, P. K. Senecal, H. J. Curran, Appl. Energy Comb. Sci., in press (2025).

C3MechLite: An Integrated Component Library of Compact Kinetic Mechanisms for Low-Carbon, Carbon Neutral and Zero-Carbon Fuels, Y. Murakami, Q.-D. Wang, S. Liu, Y. Zhu, P. Wang, L. Pratali Maffei, R. Langer, T. Faravelli, H. Pitsch, S. J. Klippenstein, J. Bergthorson, G. Bourque, K. Senecal, H. Curran, Appl. Energy Comb. Sci., in press (2025).

Study on Ammonia and Dimethyl Ether Oxidation and Kinetic Interaction up to 100 Atm, B. Mei, Z. Wang, W. Xu, A. Thawko, Y. Cao, S. J. Klippenstein, Y. Ju, Combust. Flame, 281, 114428 (2025). DOI: 10.1016/j.combustflame.2025.114428

A Theoretical Kinetic Study of ĊH3 + ṄH2: From Electronic Structure to NH3/CH4 Combustion Modelling Implications, Y. Zhu, S. J. Klippenstein, H. J. Curran, C.-W. Zhou, Combust. Flame, 277, 114232 (2025). DOI: 10.1016/j.combustflame.2025.114232

Experimental and Fuel-Surrogates Modeling Study of the High Pressure Pyrolysis of Specialty Cetane Number Fuels: Implications for Fall-Off in Ethylene Unimolecular Dissociation, M. Abdulrahman, S. Hossain, R. Sivaramakrishnan, S. J. Klippenstein, P. T. Lynch, E. K. Mayhew, K. Brezinsky, Combust. Flame, 277, 114222 (2025).DOI: 10.1016/j.combustflame.2025.114222

Accurate Dehydrogenation Enthalpies Dataset for Liquid Organic Hydrogen Carriers, R. S. Assary, H. Harb, S. N. Elliott, L. Ward, I. T. Foster, S. J. Klippenstein, L. A. Curtiss, Scientific Data 12, 171, (2025). DOI: 10.1038/s41597-025-04468-0

Flame Kinetics at Scramjet-Engine-Relevant Conditions: Role of Prompt Dissociation of Weakly-Bound Radicals, A. Kokernak, J. Matthew, R. Sivaramakrishnan, S. J. Klippenstein, J. Jayachandran, Combust. Flame 272, 113834 (2025). DOI: 10.1016/j.combustflame.2025.113834

An Experimental, Theoretical, and Kinetic Modeling Study of the N2O-H2 System: Implications for N2O + H, P. Glarborg, E. Fabricius-Bjerre, T. K. Joensen, H. Hashemi, S. J. Klippenstein, Combust. Flame 271, 113810 (2025). DOI: 10.1016/j.combustflame.2025.113810

Association Kinetics for Perfluorinated n-Alkyl Radicals, H. Ram, Y. Georgievskii, S. N. Elliott, S. J. Klippenstein, J. Phys.Chem. A 129, 555-569  (2024). DOI: 10.1021/acs.jpca.4c07388

 

A Photochemical PHO Network for Hydrogen-Dominated Exoplanet Atmospheres, E. K. H. Lee, S.-M. Tsai, J. I. Moses, J. M. C. Plane, C. Visscher, S. J. Klippenstein, Astrophys. J. 976, 231 (2024). DOI: 10.3847/1538-4357/ad8915

 

Infrared Fingerprint and Unimolecular Decay Dynamics of the Hydroperoxyalkyl Intermediate (•QOOH) in Cyclopentane Oxidation, Y. Qian, T. K. Roy, D. Valente, E. Moya Cruz, M. C. Kozlowski, A. Della Libera, S. J. Klippenstein, M. I. Lester, J. Phys. Chem. A 128, 9240-9250 1(2024). DOI: 10.1021/acs.jpca.4c05677

 

Competing Radical and Molecular Channels in the Unimolecular Dissociation of Methylformate, J. Cho, N. J. Labbe, L. B. Harding, S. J. Klippenstein, R. Sivaramakrishnan Proc. Combust. Inst. 40, 105684 (2024). DOI: 10.1016/j.proci.2024.105684

Systematic Exploration of the Thermochemistry for a Set of Peroxy Hydroperoxy-Alkyl Radicals, S. N. Elliott, C. R. Mulvihill, M. K. Ghosh, H. J. Curran, S. J. Klippenstein, Proc. Combust. Inst. 40, 105618 (2024). DOI: 10.1016/j.proci.2024.105618

High Pressure Ammonia/Methanol Oxidation up to 100 Atm, Z. Wang, B. Mei, N. Liu, A. Thawko, X. Mao, H. Zhao, P. Glarborg, S. J. Klippenstein, Y. Ju, Proc. Combust. Inst. 40, 105489 (2024). DOI: 10.1016/j.proci.2024.105489

Resolving Discrepancies Between Theory and Experiment for the NCN + H Reaction, R. Sivaramakrishnan, S. J. Klippenstein, Proc. Combust. Inst. 40, 105403 (2024). DOI: 10.1016/j.proci.2024.105403

On the Prediction of Pressure Effects for the Combination Kinetics of Two Alkyl Radicals with the Geometric Mean Rule, F. Citrangolo Destro, R. Fournet, B. Sirjean, S. J. Klippenstein, Proc. Combust. Inst. 40, 105380 (2024). DOI: 10.1016/j.proci.2024.105380

Infrared Signature of the Hydroperoxyalkyl Intermediate (•QOOH) in Cyclohexane Oxidation: An Isomer-Resolved Spectroscopic Study, T. K. Roy, Y. Qian, C. A. Sodjak, Marisa C. Kozlowski, S. J. Klippenstein, M. I. Lester, J. Chem. Phys. 161, 034302 (2024). DOI: 10.1063/5.0219431

High-Pressure Oxidation of Hydrogen Diluted in N2 with Added H2O or CO2 at 100 Atm in a Supercritical-Pressure Jet-Stirred Reactor, H. Zhao, C. Yan, G. Song, A. W. Jasper, S. J. Klippenstein, Y. Ju, Combust. Flame 266, 113543 (2024). DOI: 10.1016/j.combustflame.2024.113543

Radical Stereochemistry: Accounting for Diastereomers in Kinetic Mechanism Development, A. V. Copan, K. B. Moore III, S. N. Elliott, C. R. Mulvihill, L. Pratali Maffei, S. J. Klippenstein, J. Phys. Chem. A, 128, 3711-3725 (2024). DOI: 10.1021/acs.jpca.4c01060

Quasi-Classical Trajectory Calculation of Rate Constants Using an Ab-Initio Trained Machine Learning Model (aML-MD) with Multi-Fidelity Data, Z. Shi, A. D. Lele, A. W. Jasper, S. J. Klippenstein, Y. Ju, J. Phys. Chem. A, 128, 3449-3457, (2024). DOI: 10.1021/acs.jpca.4c00750

Isomer-Resolved Unimolecular Dynamics of the Hydroperoxyalkyl Intermediate (•QOOH) in Cyclohexane Oxidation, Y. Qian, T. K. Roy, A. W. Jasper, C. A. Sodjak, M. C. Kozlowski, S. J. Klippenstein, M. I. Lester, Proc. Nat. Acad. Sci. 121, e2401148121 (2024). DOI: 10.1073/pnas.2401148121

The Role of Stereochemistry in Combustion Processes, S. N. Elliott, K. B. Moore III, C. R. Mulvihill, A. V. Copan, L. Pratali Maffei, S. J. Klippenstein, WIREs, Comput. Mol. Sci. 024;14:e1710 (2024). DOI: 10.1002/wcms.1710

Observational Evidence for Criegee Intermediate Oligomerization Reactions Relevant to Aerosol Formation in the Troposphere, R. L. Caravan, T.J.  Bannan, F. A. F. Winiberg, M. A. H. Khan, A. C. Rousso, A. W. Jasper, S. D. Worrall, A. Bacak, P. Artaxo, J. Brito, M. Priestley, J. D. Allan, H. Coe, Y. Ju, D. L. Osborn, N. Hansen, S. J. Klippenstein, D. E. Shallcross, C. A. Taatjes, C. J. Percival, Nat. Geosci., 17, 219-226 (2024). DOI: 10.1038/s41561-023-01361-6

An Experimental, Theoretical, and Kinetic Modeling Study of Post-Flame Oxidation of Ammonia, J. Jian, H. Hashemi, H. Wu, P. Glarborg, A. W. Jasper, S. J. Klippenstein, Combust. Flame, 261, 113325 (2024). DOI: 10.1016/j.combustflame.2024.113325

OH Roaming During the Ozonolysis of a-Pinene: A New Route to Highly Oxygenated Molecules?S. J. Klippenstein, S. N. Elliott, J. Phys. Chem. A, 127, 10647-10662 (2023). DOI: 10.1021/acs.jpca.3c05179 Lester Festschrift Issue