Special Issue Preface pubs.acs.org/JPCA
Autobiography of Joel M. Bowman
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Although he stuttered occasionally, he was a brilliant lecturer and also a natty dresser. I did an independent project with him on the Ising Model in an application to the helix−coil transition in DNA. I also did summer research with Chester T. Okonski, working mainly with a senior visitor, Tae-Kyu Ha, who was running semiempirical quantum chemistry calculations in support of the experimental work being done in the Okonski lab. In 1968, during the height of antiwar protests, all hell broke loose on the campus. The National Guard was enforcing curfews, which I regularly violated by walking back from studies in some secluded spot in the Physics Library; helicopters were overhead day and night, etc. I graduated in1969 and headed for the serenity of Caltech. Although socially serene, Caltech was intellectually intense. Shortly after I got there, I heard about Aron Kuppermann’s group and decided to chat with Don Truhlar, who was just leaving the group to take up his position at Minnesota. Don encouraged me to consider joining Aron’s group, which was doing mostly experimental work then. Aron was very enthusiastic about reactive scattering theory and had a couple of interesting projects ready to go. My first project was to compare quasiclassical and quantum reaction probabilities (previously calculated by Truhlar) for collinear (two degrees of freedom) H+H2 using a realistic potential energy surface. That work resulted in my first publication and showed quantitatively the differences between exact quasiclassical and quantum reaction probabilities. Two highlights were the contribution of tunneling in two degrees of freedom and also, at higher energies, a striking difference that would soon after be clearly identified as a Feschbach resonance. Soon after, more analysis of the quantum wave functions led to quantitative tests of the vibrationally adiabatic theory and also visualization of current density and streamlines both in the deep tunneling region, which clearly showed “corner-cutting”, and at the highenergy resonance. The time at graduate school was for me, as it is for many, one of transition from student to researcher, in short, a life-changing experience. My close contact with Aron and his group as well as the atmosphere created by the other faculty and a host of super fellow graduate students, including Bill McCurdy, George Schatz, and Al Wagner, at Caltech played a major part in this transformation. In 1974, I moved to Illinois Institute of Technology in Chicago, as Assistant Professor, directly from Caltech. The academic job market was terrible in the early 70s, and Aron recommended that I take the position instead of accepting a postdoc from a couple of excellent offers. Soon after I arrived at IIT, Al Wagner set up a collaboration with him and the theory group in Chemistry at Argonne National Laboratory. Later, Thom Dunning arranged for me to have a Faculty appointee position in the Chemistry Division from 1978 to 1991. George Schatz, who was at Northwestern, also held this appointment. Thom built up a strong theory group. We’d all meet up weekly
started my education at the impoverished Atherton Elementary School in Dorchester, a working-class section of Boston. In the third grade, my family moved to Brookline for the sake of a better schools, and I thankfully transferred to the Edward Devotion School. Devotion had a library, cafeteria, gymnasium, and, most of all, excellent teachers. Two years later, I enrolled in Hebrew School for 5 years at the conservative “K.I.” synagogue, which was/is a short walk from the Devotion school. After my day at Devotion, I went to Hebrew School from 4 to 6 pm M−Th, where I struggled to learn Hebrew and prepare for my Bar Mitzvah at age 13. So, my days were filled with a variety of learning experiences. Brookline High School came next. I was in Packard House, and in 1965, I graduated with the largest class, roughly 630, up to that time. My best Math, Chemistry, and Physics teachers were women, educated at MIT and Stanford (M.S. degrees). Today, they would surely be teaching at universities. My Chemistry teacher, Mrs. Nancy Konigsberg, was a big influence. She encouraged me to enter the high school science fair, which to my amazement led to a first prize. I went on to regional and state fairs and won prizes at those as well. My project was on “Titration of Weak and Strong Acids”. I had set up a small lab in my bedroom to conduct experiments and plot up the results. Mrs. Konigsberg gave me a couple of her college texts to read, and they were filled with cool math, including a discussion of the inflection point in the titration curve. She also introduced me to professors at Northeastern and Brandeis, who let me perform electrochemical and photometric experiments on titrations. They were extremely kind and helpful, and the laboratories were incredible to a high school kid. That experience probably set me on the path of doing science. (I was a total klutz, as I often overshot the equivalence point. That experience and later fumblings in the lab convinced me that experimental science was not in my future.) I began my university studies at UMass (Amherst) and had the good fortune to be selected for a special Freshman Chemistry course taught by Richard Stein, a brilliant and charismatic Polymer Chemist. He used Bruce Mahan’s book, University Chemistry. His lectures were practically spellbinding. I did well and felt pretty special. My sophomore year was a big disappointment by comparison, and I was looking to transfer somewhere else. Earl Mortensen of H+H2 fame with Kenneth Pitzer and John Ragle, especially, steered me to Berkeley and also Chicago. I got accepted to both but for financial reasons (among others) chose Berkeley. I arrived after my first airplane ride ever in March of 1967 and felt like I had entered paradise. I took a thermo course from Kenneth Sauer, who taught from Klotz’s book (cover to cover I think, in onequarter.) Anyhow, I decided not to major in Chemistry but in what today would be termed an interdisciplinary major in Chemistry, Math, and Physics. So I cherry-picked my Chemistry courses. I took Organic from Andrew Streitweiser, another brilliant teacher, and aced the lecture but nearly flunked the lab, and P. Chem. from John Rasmussen. I took Physics courses, and one from Charles Kittel stands out. © 2013 American Chemical Society
Special Issue: Joel M. Bowman Festschrift Published: August 15, 2013 6907
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Special Issue Preface
systems. The breakthrough for us came by explicitly incorporating an invariance property of the potential into the fitting basis. That property is the invariance of the potential with respect to all permutations of like atoms. We worked out separate approaches; mine was the pedestrian “monomial symmetrization” one, and Bas’s was the more compact one based on invariant polynomial theory. Bas located software called “MAGMA”, which we purchased and which he put to amazingly good use to develop a library of invariant polynomials for many molecule types with up to 10 atoms. To date, we have published roughly 40 potential energy surfaces based on this approach. These include ones for challenging systems, such as CH5+, malonaldehyde, H5+, H7+, C3H5, CH3NO2, (H2O)2, (H2O)3, H5O2+, O(3P) + C2H4, and so forth. These potential energy surfaces have been used by us and others in reaction dynamics and vibrational calculations for fairly large systems. In addition to providing the means to investigate dynamics in complex systems, access to the complex potentials has resulted in numerous collaborations with experimental groups. In the past 10 years and up to the present, these collaborations have become a primary focus of my research group. An important collaboration was with Arthur Suits in 2004, in which the roaming pathway in H2CO photodissociation was elucidated. With new experimental capabilities, Arthur revisited a puzzling feature in the CO rotational distribution, pointed out by van Zee and Moore in 1993, and was able to correlate the feature with highly vibrationally excited H2. We performed quasiclassical trajectory calculations, using a new ab initio potential energy surface that was developed in collaboration with Larry Harding, and were able to reproduce both the puzzling feature and the new results observed by Suits. In addition, by examining tens of thousands of trajectories, we observed that some formed the H2 + CO products by a pathway that is “orthogonal” to the conventional one over the tight transition state to these products. This pathway, which was termed “roaming”, starts with the formation of incipient radicals, H and HCO, with however insufficient relative translational energy to actually form them. Unexpectedly, instead of simply re-forming the internally excited H2CO complex, in some cases, these nearly separated pairs “self-react” to directly form H2 + CO at large H−H distances, leading to vibrationally excited H2. (By contrast, trajectories that follow the conventional tight transition-state pathway produce vibrationally cold H2.) Arthur and I subsequently wrote a number of joint papers investigating this roaming pathway in detail. Shortly after the joint paper with Arthur, similar roaming pathways were reported in numerous other systems. The next one chronologically was in photodissociation of acetaldehyde, which was correctly surmised by Paul Houston and Scott Kable to follow a roaming pathway. We subsequently collaborated with Scott, David Osborn, and Meredith Jordan to show that roaming is the dominant pathway to the molecular products CH4 + CO. A collaboration with Hanna Reisler and her group has resulted in several papers. Recent ones have focused on the dissociation energy and dynamics of the water dimer and trimer. A representation of the most recent work on the trimer, reported in a joint paper in this Festschrift, is given in the cover art. The theoretical work was performed by Emory postdocs Yimin Wang and Gabor Czakó. The other half of the cover art represents a collaboration with Bob Continetti’s group on the dissociation dynamics of the highly energized transient H3O species, formed by charge exchange between H3O+ and Cs.
at Argonne to discuss and conduct research on reaction rates of elementary combustion reactions, generally using transitionstate theory with tunneling corrections from 1d or 2d quantum calculations. (I also recall the lunches together in the cafeteria, with lots of good conversation and joking around.) Al, George, and I wrote several papers investigating these approaches, with a focus on the O(3P) + H2 reaction. Al and I also wrote papers on H + CO recombination, using a three-dimensional potential energy surface developed in collaboration with Larry Harding. The IIT years included development of the Vibrational SelfConsistent Field and Configuration Interaction approaches to molecular vibrations and reduced dimensionality quantum theories of reaction cross sections and rate constants, including “J-shifting”. I was promoted to Full Professor at IIT in1982 and had my first sabbatical at the James Franck Institute, the University of Chicago, in 1983−1984, where I was always warmly welcomed during my time at IIT. I first met Zlatko Bačić at Chicago, where he was a postdoc with John Light. I spent one month as a consultant at Bell Laboratories with John Tully in 1984. This was great fun and resulted in a pretty highly cited paper [Tully, J. C.; Chabal, Y. J.; Raghavachari, K.; Bowman, J. M.; Lucchese, R. R. Infrared Linewidths and Vibrational Lifetimes at Surfaces: H on Si (100). Phys. Rev. B: Condens. Matter 1985, 31, 1184]. In 1986, I moved to Emory University, my current academic home, as Full Professor. This was an exciting move as the Chemistry department was supporting growth in Physical Chemistry. Michael Heaven moved with me from IIT, and shortly thereafter, Ming Chang Lin joined us, as did Keiji Morokuma. My first years of research at Emory focused on further development of reduced-dimensionality quantum theories of reactive scattering to four-atom systems and further developments of J-shifting. Potential energy surfaces for HCN/ HNC isomerization and acetylene/vinylidene were developed and used in full-dimensional quantum calculations of vibrational energies and wave functions. From 1990 to 1993, I served my first term as department chair. I was fortunate to work with Cherry L. Emerson, alumnus and benefactor at Emory, and with the Emory administration to establish the Emerson Center for Scientific Computation. I was acting director from 1991 to 1993. In 1993, Keiji Morokuma arrived to be the director from 1993 to 2006. The Emerson Center had a Visiting Fellows program, which was modeled a bit after the world-famous one at JILA (which I experienced first-hand in 1994), and brought many outstanding people to Emory. I was fortunate to host Stuart Carter as a Fellow in 1996, and that resulted in an active collaboration that continues to this day. We developed the code MULTIMODE, based on the n-mode representation of the potential. We have made good of use of this code in my group; recent examples include the “line-list” spectra of C2H4 and H2O2 and lower-resolution spectra of H5+ and D5+ and CH5+. In 2003, I began my collaboration with Bastiaan Braams. This collaboration began when he responded to an inquiry I sent to “NA Digest” about Hermite interpolation in many dimensions. I was interested in this interpolation mainly for use with n-mode potential grids and possibly also to represent ab initio electronic energies in high dimensionality. Although Bas, who was trained as a theoretical plasma physicist, had a workable solution, we both decided the method did not have much of a future. Instead, during several visits to Emory, we decided to investigate global fitting of “scattered” electronic energies. The time seemed ripe for some new approaches to represent potential energy surfaces for more than four-atom 6908
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This work is also reported in a joint paper in this Festschrift. Earlier work on charge exchange between CH5+ and Cs to make the transient CH5 species was reported in a joint paper with Bob. A lively collaboration with Kopin Liu on investigating the applicability of the Polanyi rules for the reactions of F, Cl, and O atoms with CH4 and isotopologues has been stimulating. This research has also involved collaborations with Dong Hui Zhang, Hua Guo, and Dunyou Wang, who have performed reduced-dimensionality quantum calculations on these systems to compare with quasiclassical trajectory calculations done by Gabor Czakó and myself and experiment. Other collaborations and joint papers with experimental groups include those with Piero Casavecchia on intersystem crossing in O(3P) + C2H4, Mark Johnson on the IR spectrum of H5O2+, OH−(H2O), and Cl−(H2O), Dan Neumark and Knut Asmis on the IR spectra of BrHI− and BrDI−, Paul Houston and Domenico Stranges on photodissociation of allyl, David Nesbitt on the IR spectrum of CH5+, Marsha Lester on the quenching of OD* by H2, Mike Duncan and Knut Asmis on the IR spectroscopy of H5+ and D5+, and Laurie Butler on the dissociation of highly rotating CD2CD2OH. I consider these collaborations, plus numerous other ones with theoretical groups, to be the highlights of my scientific career since arriving at Emory. It must be noted that in each case, having the techniques to develop a relevant fulldimensional potential surface was our key contribution to these collaborations. It remains only for me to close with brief words of thanks. First, one perhaps trite observation: although our field thrives and advances from the drive and energy that come from within ourselves, years of experience tell me that it really advances from the drive and energy of colleagues. In short, we thrive as a community. I feel extremely fortunate to be part of “my” large community of researchersa smart, hard-working, ethical, honest, and fair group. I thank the National Science Foundation, the Department of Energy, the Office Naval Research, the Army Research Office, the National Aeronautics and Space Administration, and the American Chemical Society, who have provided financial support of my research group. I am grateful to the talented and hardworking graduate students and postdocs I have had the good fortune to advise and collaborate with. I have learned much from you. I have also learned much from the outstanding senior people I have collaborated with; thanks to you all. I also want to mention my recent experience as vice-chair-elect, vice-chair, chair-elect, and soon-to-be chair of the PHYS division of the ACS. It has been a delight to work with my fellow officers; you are a class act. Great thanks to Zlatko Bačić and Tucker Carrington for initiating and organizing this Festschrift issue and to Anne McCoy, Deputy Editor, and George Schatz, Editor-in-Chief of J. Phys. Chem. Thanks also for your collaborations and friendships over the years. Thanks to my wonderful colleagues at Emory University and to Susan Browne, in particular, for her many years of indispensible help in keeping the many daily aspects of running a group going smoothly. Finally, thanks to Pat Michaelson, my wife and fellow academic traveler. You have been a pillar of support and love.
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