About

Professor Terry Miller is an Ohio Eminent Scholar and Professor Emeritus in the Department of Chemistry and Biochemistry at The Ohio State University. He received his B.A. degree in Chemistry from the University of Kansas in 1965 and his Ph.D. degree in Chemistry from Cambridge University in 1968. His professional career includes work at Bell Telephone Laboratories from 1968 to 1984, where he became a Distinguished Member of the Technical Staff in 1983. In 1984, he joined Ohio State University as the state of Ohio's first Ohio Eminent Scholar Professor. Professor Miller's research has long centered on the spectroscopic detection and characterization of reactive chemical intermediates, which are critical in processes such as combustion, atmospheric and interstellar chemistry, plasmas, and reacting flows. His group has performed experimental and theoretical/computational spectroscopy, with recent focus on theoretical work. His collaborations include experimental groups in Engineering at Ohio State and Chemistry at the University of Louisville, as well as a theoretical group at the University of Florida. His work involves the simulation of cavity-ring-down electronic-absorption spectra of metastable molecules like triplet N2 and alkoxy radicals, key intermediates in combustion and atmospheric degradation. He investigates the fundamental basis for chemical reactivity, especially the coupling of electronic and nuclear motion beyond the Born-Oppenheimer approximation, developing models to predict spectra of reactive molecules in degenerate electron states. Professor Miller has received numerous awards, served as editor-in-chief of the Journal of Molecular Spectroscopy from 2005 to 2021, and is a Fellow of multiple scientific societies.

Research topics

• Chemistry
• Atomic physics
• Physics
• Materials science
• Photochemistry

Selected publications

• New Approachesfor Engagingthe Public and Making Sense of Their Input

  Proceedings of the Canadian Rural Revitalization Foundation · 2025-07-30

  articleOpen access1st authorCorresponding

  Municipal leaders often turn to the public (by choice or by pressure) to inform decision-making. But traditional town hall meetings or 'sticky note' workshops often raise just as many questions as they answer. New tools and methods are now available to decision and policy makers that can provide deep insights into Volatile, Uncertain, Complex and Ambiguous (VUCA) environments. These methods are NOT 'another survey', not another open mike public session. These methods engage stakeholders. And the outputs provide the best of qualitative and quantitative data gathering. We get visuals outputs (emergent patterns) but we also get the context (the stories behind the numbers). This presentation will offer case studies, plus a splash of theiry for understanding and navigating complexity.

  PublisherOA PDFDOI

• <i>Ab initio</i> simulation of spin-vibronic spectra of methoxy radical

  The Journal of Chemical Physics · 2025-05-08 · 3 citations

  articleOpen accessSenior author

  Despite the fact that experimental and theoretical work on the spectrum of methoxy has stretched from the microwave to the ultraviolet and proceeded for nearly 50 years, parts of the spectrum have remained a challenge to simulate theoretically and make reliable line-by-line assignments. The spectral complexity arises because the radical has a non-zero electron spin and significant vibronic coupling between the two electronic components of the ground state due to the presence of a conical intersection. This work describes a completely ab initio effort to understand and assign the spin-vibronic levels of the X̃2E state from 0 to above 3000 cm-1, a region that includes the fundamental transitions of the C-H symmetric and asymmetric stretches that have not previously been identified uniquely. A potential energy surface for methoxy was calculated at the equation-of-motion (EOM)-coupled cluster singles, doubles, and triples (CCSDT)/atomic natural orbital (ANO1) level of theory. Subsequently, this potential energy surface was fit to a quartic power series expansion of all nine vibrational normal coordinates (as determined at the minimum of the conical intersection) by the use of a machine-learning-based algorithm. After the addition of spin-orbit coupling, the spin-vibronic problem was solved using both the Krylov-Schur and Lanczos algorithms with the SOCJT3 software to converge eigenvalues up to 3500 cm-1 and their eigenvectors. The latter were used, in conjunction with the calculated dipole moment and its derivatives (calculated using finite differences at the EOM-CCSDT/ANO1 level), to determine spectral intensities for the spin-vibronic spectra. The calculated transition frequencies and intensities were used to simulate and assign the observed transitions of the spin-vibronic spectra of the radical. The credibility of the assignments and their significance is discussed in detail.

  PublisherOA PDFDOI

• Molecules with Spin and Vibronic Coupling Effects: A Computational Perspective

  Journal of Physics Conference Series · 2024-05-01 · 5 citations

  articleOpen access

  Abstract While fundamental to molecular quantum mechanics, limitations of the Born-Oppenheimer Approximation (BOA) have long been known. Nonetheless, calculations that include molecular interactions, such as vibronic coupling and electron spin effects, that violate the BOA have remained a challenge due to their large demand on computational resources. The purpose of this paper is to describe two complementary software programs, SOCJT and XSIM, designed for efficient calculations that include these interactions. The programs are sufficiently general and user friendly that they can be readily applied to a variety of molecules of different symmetries, state degeneracies, and interaction strengths. The programs can typically produce spin-vibronic eigenvalues and eigenvectors with sufficient accuracy for the analysis and interpretation of molecular spectra with features attributable to violations of the BOA. The two programs utilize different matrix representations of the molecular Hamiltonian, with XSIM being Cartesian based and SOCJT being cylindrically based, and their advantages/disadvantages are discussed. Several algorithms can be chosen to obtain the Hamiltonian’s eigenvalues and eigenvectors and their speed and memory usage are compared. Examples of application of SOCJT and XSIM to explain spectral observations for particular molecules are briefly reviewed.

  PublisherOA PDFDOI

• Calculated and Empirical Values of Vibronic Transition Dipole Moments of Reactive Chemical Intermediates for Determination of Concentrations

  The Journal of Physical Chemistry A · 2023-05-22 · 3 citations

  articleCorresponding

  Absorption spectroscopy has long been known as a technique for making molecular concentration measurements and has received enhanced visibility in recent years with the advent of new techniques, like cavity ring-down spectroscopy, that have increased its sensitivity. To apply the method, it is necessary to have a known molecular absorption cross section for the species of interest, which typically is obtained by measurements of a standard sample of known concentration. However, this method fails if the species is highly reactive, and indirect means for attaining the cross section must be employed. The HO2 and alkyl peroxy radicals are examples of reactive species for which absorption cross sections have been reported. This work explores and describes for these peroxy radicals the details of an alternative approach for obtaining these cross sections using quantum chemistry methods for the calculation of the transition dipole moment upon whose square the cross section depends. Likewise, details are given for obtaining the transition moment from the experimentally measured cross sections of individual rovibronic lines in the near-IR ÖX̃ electronic spectrum of HO2 and the peaks of the rotational contours in the corresponding electronic transitions for the alkyl (methyl, ethyl, and acetyl) peroxy radicals. In the case of the alkyl peroxy radicals, good agreement for the transition moments, ≈20%, is found between the two methods. However, rather surprisingly, the agreement is significantly poorer, ≈40%, for the HO2 radical. Possible reasons for this disagreement are discussed.

  PublisherDOI

• The FluidFlower Validation Benchmark Study for the Storage of CO$$_2$$

  Transport in Porous Media · 2023-08-18 · 53 citations

  articleOpen access

  Abstract Successful deployment of geological carbon storage (GCS) requires an extensive use of reservoir simulators for screening, ranking and optimization of storage sites. However, the time scales of GCS are such that no sufficient long-term data is available yet to validate the simulators against. As a consequence, there is currently no solid basis for assessing the quality with which the dynamics of large-scale GCS operations can be forecasted. To meet this knowledge gap, we have conducted a major GCS validation benchmark study. To achieve reasonable time scales, a laboratory-size geological storage formation was constructed (the “FluidFlower”), forming the basis for both the experimental and computational work. A validation experiment consisting of repeated GCS operations was conducted in the FluidFlower, providing what we define as the true physical dynamics for this system. Nine different research groups from around the world provided forecasts, both individually and collaboratively, based on a detailed physical and petrophysical characterization of the FluidFlower sands. The major contribution of this paper is a report and discussion of the results of the validation benchmark study, complemented by a description of the benchmarking process and the participating computational models. The forecasts from the participating groups are compared to each other and to the experimental data by means of various indicative qualitative and quantitative measures. By this, we provide a detailed assessment of the capabilities of reservoir simulators and their users to capture both the injection and post-injection dynamics of the GCS operations.

  PublisherOA PDFDOI

• The FluidFlower International Benchmark Study: Process, Modeling Results, and Comparison to Experimental Data

  arXiv (Cornell University) · 2023-02-09 · 11 citations

  preprintOpen access

  Successful deployment of geological carbon storage (GCS) requires an extensive use of reservoir simulators for screening, ranking and optimization of storage sites. However, the time scales of GCS are such that no sufficient long-term data is available yet to validate the simulators against. As a consequence, there is currently no solid basis for assessing the quality with which the dynamics of large-scale GCS operations can be forecasted. To meet this knowledge gap, we have conducted a major GCS validation benchmark study. To achieve reasonable time scales, a laboratory-size geological storage formation was constructed (the "FluidFlower"), forming the basis for both the experimental and computational work. A validation experiment consisting of repeated GCS operations was conducted in the FluidFlower, providing what we define as the true physical dynamics for this system. Nine different research groups from around the world provided forecasts, both individually and collaboratively, based on a detailed physical and petrophysical characterization of the FluidFlower sands. The major contribution of this paper is a report and discussion of the results of the validation benchmark study, complemented by a description of the benchmarking process and the participating computational models. The forecasts from the participating groups are compared to each other and to the experimental data by means of various indicative qualitative and quantitative measures. By this, we provide a detailed assessment of the capabilities of reservoir simulators and their users to capture both the injection and post-injection dynamics of the GCS operations.

  PublisherOA PDFDOI

• Time-resolved measurements of HO2 radical in a heated plasma flow reactor

  Combustion and Flame · 2022-03-22 · 11 citations

  articleOpen access
  PublisherOA PDFDOI

• VIBRONIC ANALYSIS OF MOLECULES WITH QUASI-DEGENERATE ELECTRONIC STATES

  Proceedings of the 2022 International Symposium on Molecular Spectroscopy · 2022-06-21

  articleOpen accessSenior author
  PublisherOA PDFDOI

• ELECTRONIC SPECTROSCOPY OF THE Ã − X TRANSITIONS OF JET-COOLED CALCIUM MONOALKOXIDE RADICALS: SPIN-VIBRONIC STRUCTURE OF NONLINEAR MOLECULES AS CANDIDATES FOR DIRECT LASER COOLING

  Proceedings of the 2022 International Symposium on Molecular Spectroscopy · 2022-06-21

  articleOpen access
  PublisherOA PDFDOI

• CONCENTRATION DETERMINATIONS FOR REACTIVE CHEMICAL INTERMEDIATES USING EMPIRICALLY DETERMINED AND THEORETICALLY CALCULATED TRANSITION PROBABILITIES

  Proceedings of the 2022 International Symposium on Molecular Spectroscopy · 2022-06-21

  articleOpen access
  PublisherOA PDFDOI

Recent grants

• Theoretical studies of spectroscopic and dynamic implications of large amplitude vibrations

  NSF · $448k · 2012–2016

• The Spectroscopy of Chemical Intermediates and Other Transient Species

  NSF · $600k · 1990–1994

• High Resolution Spectroscopy of Reactive Chemical Intermediates and Related Studies

  NSF · $649k · 2010–2014

• Application of Advanced Spectroscopic Techniques to the Study of Key Reactive Chemical Intermediates

  NSF · $623k · 2005–2009

• Spectroscopic Detection and Characterization of Chemical Intermediates

  NSF · $903k · 1994–1999

Frequent coauthors

• V. E. Bondybey

  Technical University of Munich

  95 shared

• James M. Williamson

  77 shared

• Christopher C. Carter

  Loyola University Chicago

  47 shared

• Lian Yu

  University of Wisconsin–Madison

  37 shared

• Jinjun Liu

  35 shared

• J. H. English

  University of California, Santa Barbara

  33 shared

• Robert S. Freund

  33 shared

• Stephen Foster

  International Water Association Publishing

  31 shared

Awards & honors

• William F. Meggars Award (Optical Society of America - 1993)
• Bomem-Michaelson Award (Coblentz Society - 1995)
• Bourke Medal (Royal Society of Chemistry - 1998)
• Broida Prize (American Physical Society - 1999)
• Plyler Prize (American Physical Society - 2009)