Memorial Tributes: Volume 26
Tribute Author
Membership Directory

Search this Publication

  • JAMES A. MILLER (1946-2021)



    JAMES ANGUS MILLER, a preeminent combustion chemist who spent most of his career at Sandia National Laboratories, died peacefully at his home in the early hours of October 3, 2021, at the age of 75.

    Jim was born August 16, 1946, in Huntington, West Virginia, to Angus and Daisy Tabor Miller, their only child. His brain was occupied by nuanced baseball and basketball game statistics and then a strong scientific interest. Recognition of his mental capacity led to his designation as high school valedictorian. The first in his family to go to college, he graduated with a bachelor of science degree in aerospace engineering from the University of Cincinnati in 1969.

    His co-op placement took him to the San Francisco Bay Area, but he soon crossed the country to earn his master’s in aerospace engineering from Cornell (1970), where he stayed to do his PhD in the Mechanical and Aerospace Engineering Program. Interestingly, his early work was experimental: he used the laser schlieren technique to study the oxidation and pyrolysis of methane. Importantly, the special arrangements of Cornell’s engineering program allowed him to pursue his intellectual passion in the more fundamental aspects of science.

    And it was at Cornell that he met Constance Warren, a student of the same program, whom he married in 1971. Connie got a job offer as faculty at the University of California, Berkeley in 1974, and the couple settled in Orinda.

    Jim spent 36 years at Sandia National Laboratories’ Combustion Research Facility, retiring in 2010 as a Distinguished Member of Technical Staff. From then on, he was affiliated with Argonne National Laboratory’s Chemical Dynamics group, still largely working from California.

    Jim Miller was informally inducted into the combustion hall of fame at a very early age, when, as one of the early developers, he set the theoretical foundations of CHEMKIN, the most widely used software program for combustion chemistry modeling for over 30 years. This was merely one of his many groundbreaking contributions, and he will surely be remembered as one of the fathers of modern combustion chemistry. His remarkable influence spreads beyond the sphere of combustion to the heart of fundamental gas-phase chemical reaction theory.

    At the beginning of his career, motivated by environmental concerns and the energy crisis of the 1970s, he recognized the importance of chemical modeling. However, when he started working at Sandia in 1974 it was not clear what combustion chemistry should or could do and, based on his own account, it took some thinking to establish the framework that many now view as given. Joining the vision of one of the tribute coauthors (RJK), he worked on CHEMKIN to create a tool that can be used beyond simple hydrogen-air simulations, and as Sandia’s Combustion Research Facility became one of the most important centers for combustion research in the 1980s, visiting scholars spread the early versions of the code around the world.

    Jim’s initial mechanistic interest concerned high-temperature nitrogen chemistry, which culminated in his landmark paper with Tom Bowman (NAE 2013) in 1989.1 The paper has more than 3800 citations and counting, and not just for historic reasons but because it captured the details of high-temperature nitrogen chemistry correctly. (CHEMKIN,2 while never published as an article, has been cited more than 6600 times just through its internal Sandia report. We mention this because Jim never hid his pride in these citations, a characteristically honest admission.) 

    Although Jim is doubtless most widely recognized for his pioneering fundamental research in combustion-related chemical kinetics, he also made seminal contributions concerning interactions between chemically reacting fluid mechanics and complex chemical kinetics. Working with RJK and Michael E. Coltrin, Jim played a central role in the fluid-mechanical boundary-layer formulation of a model that enabled the incorporation of detailed chemical kinetics in models of chemical vapor deposition for semiconductor fabrication. A 2002 survey by the Electrochemical Society identified the 1984 paper3 documenting that research as one of the 25 most significant papers published in the society’s journal since 1945.

    Jim was similarly instrumental in the fluid-mechanical formulation of a stagnation-flow model that enabled the prediction and interpretation of flame speeds under high-strain-rate conditions. The 1989 paper documenting this research was recognized by the 1990 Silver Medal from the Combustion Institute (CI).4 These fluid-mechanical formulations are used widely today in laboratory-scale research and for technology applications involving complexities of chemically reacting flow.

    Around 1990 his attention turned to another chemical problem of societal importance: soot formation. His ideas on the role of resonantly stabilized radicals, combined with Carl Melius’s development of high-quality ab initio methods, made it possible to work out the details of the first aromatic ring formation through the propargyl self-recombination reaction. They published the results in Combustion and Flame,5 and for a long time it was the journal’s most cited paper. He was also very pleased with the wide appreciation of his 1996 Plenary Lecture at the 26th International Combustion Symposium in Naples, Italy, where he reviewed the connection between fundamental kinetics and combustion chemistry for ring formation, H + O2, and two NOx issues.6

    His successes with nitrogen chemistry and soot formation indicated to Jim that accurate quantum chemistry combined with proper dynamics (always in balance!) can be transformative to combustion chemistry modeling more broadly. He went on to study the low-temperature oxidation chemistry of ethyl and propyl radicals with SJK7 and Craig A. Taatjes,8 work that firmly established concepts still echoed in countless papers on autoignition published every year.

    A recurring theme in the reactions Jim studied was that they happen over multiple wells, requiring the coupling of not just electronic structure and transition-state theory but also of collisional energy transfer in a consistent master equation formalism. His focus on the fundamentals of chemical kinetics occurring over complex multiple-well multiple-channel potential energy surfaces was driven by his desire to accurately predict the kinetics of the propargyl + propargyl recombination reaction. This finally became possible when, in collaboration with SJK, an analytic result was derived that connected the eigensolutions of the master equation with the phenomenological rate coefficients required for kinetic modeling. Jim then went on a crusade, armed with the gentle tool of review papers, to argue for the proper mathematical treatment of these complex chemical networks.

    The aughts represented the golden years in Jim’s career—literally, as he received the CI’s Bernard Lewis Gold Medal in 2006. He also became a fellow of the American Physical Society (2004) and of the American Association for the Advancement of Science (2006), and, to his delight, in 2007 the Journal of Physical Chemistry A dedicated a Festschrift to him.9 In 2008 he was elected to the National Academy of Engineering.

    And he kept going. While he continued working on long-term collaborations (for example, his work with one of the coauthors [PG] led to a new standard for NOx modeling10) and new chemical systems (including a 2008 Combustion Symposium distinguished kinetics paper,11 with one of the coauthors [JZ], on the reaction of hydroxyethyl radicals with O2), he also shifted his focus to energy transfer (in collaboration with Ahren Jasper), and participated in the formulation of the prompt dissociation phenomenon (with Raghu Sivaramakrishnan and others). At the same time he maintained strong ties with experimentalists (including a focus on understanding the synchrotron-based flame speciation experiments led by one of the coauthors [NH]), another hallmark of his research.

    With his questing mind, from a lifetime of work on chemical reactions and mechanisms a new goal emerged: the creation of the first, fully theoretically based and untuned C0–C3 chemical model, which he named ThInK (theoretically informed kinetics). The curated mechanism is based on the newest and most accurate calculations by him and his group of collaborators. Many of the modern concepts enabling this mechanism are described in his last paper: “Combustion chemistry in the twenty-first century: Developing theory-informed chemical kinetics models,” published in Progress in Energy and Combustion Science in March 2021.

    Jim’s scientific method appeared to be slow, but he got things right the first time. His methodical approach left a voluminous paper trail: handwritten green engineering papers with entire sections of manuscripts written without apparent corrections.

    He had several golden retrievers, and there was something in him that resembled the spirit of these wonderful creatures. He was very loyal to the people he considered to be his associates. They might have had different ranks, but titles did not matter to him (which sometimes got him into trouble at Sandia). 

    And his loyalty never stood in the way of his honesty and his commitment to good science, even if he had to pick an occasional fight for it.

    He dedicated his life to science; even after the onset of illness he never lost his warmth and his interest in the world and the people around him. He liked traveling, was passionate about politics and baseball (especially the Giants), had a sweet tooth, and was very proud of his family. He enthusiastically cheered for a younger generation of combustion chemists (even if they knew nothing about baseball) and taught them a great deal.

    Jim is survived by Connie, his wife of 50 years, and their children Abigail Emma and Nathan James (Mariann).

    We miss him.

    1 Miller JA, Bowman CT. 1989. Mechanism and modeling of nitrogen chemistry in combustion. Progress in Energy and Combustion Science 15(4):287–338.
    2 Kee RJ, Rupley FM, Miller JA. 1989. CHEMKIN-II: A Fortran Chemical Kinetics Package for the Analysis of Gas-Phase Chemical Kinetics. Available at

    3 Coltrin M, Kee R, Miller JA. 1984. A mathematical model of the coupled fluid mechanics and chemical kinetics in a chemical vapor deposition reactor. Journal of the Electrochemical Society 131(2):425–33.
    4 Kee RJ, Miller JA, Evans GH, Dixon-Lewis G. 1990. A computational model of the structure and extinction of strained, opposed flow, premixed methane-air flames. Symposium (International) on Combustion 22(1):1479–94. 
    Miller JA, Melius CF. 1992. Kinetics and thermodynamic issues in the formation of aromatic compounds in flames of aliphatic fuels. Combustion and Flame 91:21–39.
    6 Miller JA. 1996. Theory and modeling in combustion chemistry. Symposium (International) on Combustion 26(1):461–80.
    7Miller JA, Klippenstein SJ. 2001. The reaction between ethyl and molecular oxygen II: Further analysis. International Journal of Chemical Kinetics 33(11):654–66.
    DeSain JD, Klippenstein SJ, Miller JA, Taatjes CA. 2003. Measurements, theory, and modeling of OH formation in ethyl + O2 and propyl + O2 reactions. Journal of Physical Chemistry A 107(22):4415–27.

    9Journal of Physical Chemistry A 111(19):3673–4415.
    10 Glarborg P, Miller JA, Ruscic B, Klippenstein SJ. 2018. Modeling nitrogen chemistry in combustion. Progress in Energy and Combustion Science 67:31–68.
    11Zádor J, Fernandes RX, Georgievskii Y, Meloni G, Taatjes CA, Miller JA. 2009. The reaction of hydroxyethyl radicals with O2: A theoretical analysis and experimental product study. Proceedings of the Combustion Institute 32:271–77.