Special Issue Preface pubs.acs.org/JPCA
Preface: Mark S. Gordon Published as part of The Journal of Physical Chemistry virtual special issue “Mark S. Gordon Festschrift”. chemistry pranks that he would play as a student. This, of course, inspired Mark to emulate those pranks (this is for the out-of-control group, and you know who you are!) and inspired him to learn more about chemistry. Mark stayed in touch with Mr. Joyce throughout his college years, and they always enjoyed discussing what Mark was learning. His only disappointment with Mark was that Mark became a physical chemist instead of an organic chemist! As an undergraduate at Rensselaer Polytechnic Institute (RPI), Mark hated being in lab. He was always the last one to finish the laboratories in organic chemistry, since he was being very careful to learn from other’s mistakes. Note that Mark was successful in this, since he was the only one in his class who did not have a fire or explosion at some point in the class. Even Mark’s physical chemistry and instrumental laboratories were disappointing and boring, since there was no student instrumentation at the time, and the students were not allowed to touch the instrumentationonly Teaching Assistants were allowed to do the experiments. Analytical lab was also boring, since they wanted answers to the nth decimal point, and you had to use slide rules at the time. However, Mark loved the theory and concepts of chemistry, and this kept him interested. Professor Strong and Professor Waite were the professors who introduced Mark to the ideas of quantum mechanics. Their patience with Mark, as he kept showing up to their offices with questions, and their general enthusiasm for science reinforced Mark’s interest in pursuing quantum mechanics. Mark wrote his senior thesis on applications of Hückel theory to biomolecules. Mark decided to go to Carnegie Tech by looking through the Directory of Graduate Research and realizing that Professor Bob Parr was on the faculty. Remember there was no e-mail or Internet at that time, so getting information was much more difficult! When Mark got to Carnegie Tech, he found out that Bob had left to go to Johns Hopkins. Frank Ellison was the only one doing theory there at the time, but it was not in a field of interest to Mark. Mark was looking for a new academic home by the middle of the first year when he heard that John Pople was coming to Carnegie Tech. Mark immediately stopped looking at other places. He and Jerry Segal camped out on John’s doorstep to make sure that they were the first two students that John took as graduate students. Since John would go back to England every summer, Mark built a strong relationship with Professor Bob Kurland, an NMR expert, who helped Mark when he had questions. It was through Bob that Mark realized that the “12” exponent in the Leonard-Jones potential was an empirical fitreinforcing Mark’s distaste for fitted parameters. The graduate students and the atmosphere in John Pople’s research group created a wonderful environment for Mark during his graduate years. The people included Neil Ostlund, Paul Dobosh, Marshall Newton, Jim McIver, David Beveridge,
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ark turns 75 this year!! It is our pleasure and privilege to organize this virtual special issue in honor of Mark’s many scientific accomplishments and personal interactions throughout his career. Since a fairly complete overview of Mark’s professional career and biography was given in the preface to the special issue in honor of Mark’s 65th birthday (K. K. Baldridge, M. W. Schmidt, Theor. Chem. Acc. 2008, 120, 1− 4), we decided to focus more on the motivational side of Mark’s science career in this forward. If you know anything about Mark Gordon, you know that he is a storyteller. He has a story for almost any topic and is not shy about sharing them with others! We decided that the best way to find out the motivating factors in Mark’s career was to sit down with him and let him tell some stories. Included here are just some of the highlights on the influences that shaped Mark’s career, since a whole book could be written from the stories that Mark can tell! Mark’s earliest influence was his father, Bernard Gordon Bernie to his friends, a salesman who never went to college. Bernie believed in a strong work ethic, but he also was convinced that science was the next frontier for new opportunities. Back in the late 1950s there were only three television (TV) stations at the time, but if there was anything related to science on TV, Bernie made sure that Mark was sitting down and watching it. He was fascinated by science and was convinced that the way to make your way through the world was to be a scientist. These shows were really interesting to Mark and helped to spur his interest in science. Another early influence was Mark’s high-school chemistry teacher, Mr. Joyce. Mr. Joyce was a child of the Great Depression and had to go to work instead of continuing to graduate school. He had a great enthusiasm for science (teaching chemistry and biology) and told stories about the © 2017 American Chemical Society
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do their own thing, trust them, and they will do excellent work. Furthermore, a systematic approach in research endeavors is common to philosophies of both John and Klaus. Mark also learned not to take himself too seriously. These are all lessons that Mark has passed (or tried to pass) on to his own students. As most people know, Mark is well-known for his early and continued work in silicon chemistry. Mark had been interested in silicon since he was a senior at RPI. Mark’s best friend as an undergraduate was Warren Giering, whose mother’s farm Mark lived on during his senior year. The two seniors both had wild ideas and great fun together. Warren did his senior project about organosilicon chemistry and told Mark that silicon did not form double bonds. Neither of them understood why and this question stuck with Mark. When Mark went to graduate school, Mark had wanted to learn about silicon chemistry. But John said, “I don’t understand carbon yet,” (not a surprising answer for those who knew John) and he did not want to work on silicon. So, Mark learned more about chemical theory in both his graduate and postdoctoral research, including fundamentals of methods and bonding. When he got to North Dakota State University (NDSU), Mark wanted to extend semiempirical theory to the third row of the periodic table with silicon as the motivation. As an aside, Mark had early interests in excited states and photochemistry as well. Bob Koob, a photochemist interested in alkanes, was one of the exciting (pun intended) and active researchers at NDSU. (As another aside, Mark and Bob are great friends. It all started at Mark’s interview when Mark went to Bob’s house for dinner with Bob’s wife Yvonne and their five children, watched a chemistry/biochemistry softball game, and spent many hours in the hotel parking lot talking about religion and life!) Bob and Mark started looking at ground-state virtual orbitals of alkanes to try to understand the excited states of alkanes. This led Mark to want to look at excited states, and he wrote an INDO CIS code and performed calculations with his graduate student Pat Saatzer. Of course, Rydberg states are important for these molecules in their vertical excited states, and Rydberg and valence states can mix in CI. So, Mark moved to ab initio wave functions with Pat and Jim Caldwell by adding in proper Rydberg basis functions. While the vertical states indeed are mostly Rydberg in character, they do have significant valence character, especially when the geometry relaxes (i.e., when the structures dissociate). This collaboration with Bob Koob motivated Mark to engage with more experimentalists. Now back to the silicon story. In the next couple of years, Dick Hildebrandt (whose research encompassed structure determination by electron diffraction and by force-field predictions) and Phil Boudjouk (a now well-known silicon chemist) joined NDSU, completing the quartet with Mark and Bob. The four of them had a wonderful collaboration and started to develop a strong reputation at NDSU in organosilicon chemistry. This is where Mark’s deep interest in silicon took off, and his understanding of hybridization applying only to carbon really cemented. His work in the area of silicon chemistry demonstrated the need for consideration of multiconfigurational and multireference wave functions in a variety of systems, which has been a hallmark of his career. Important interactions were also forged when Mark attended an American Conference on Theoretical Chemistry meeting in Jackson Hole, Wyoming, where he met “the Larrys” (Larry Davis and Larry Burgraff) at a poster session. Through them, Mark met Bob Damrauer from the University of Colorado Denver. These
David Santry, Keith Miller, Herb Fischer, and Warren Hehre all who have had an impact in our field. Mark helped to mentor Neil and Warren as part of his graduate responsibilities, and this helped him to grow in this aspect of his career. While Mark has many stories of these days, one of these stories captures several lessons that he learned from John. John was a very hands-off advisor once he was convinced that you were on the right pathone of Mark’s philosophies as well. On the basis of some conversations with John, Mark had been working on a geometry optimization program based on steps on a parabola. While John was away in England, Mark decided to apply his geometry optimization method to determine the rotational barrier of ethane. At that time, state-of-the-art work by Bob Parr on the rotational barrier of ethane without geometry relaxation had led to an interpretation of the results as attractive versus repulsive interactions. Mark thought that the geometry must relax during the rotation based on the vicinal interactions, which would alter this interpretation. So, he systematically studied the relaxed geometries of the staggered and eclipsed conformations using semiempirical methods and saw that indeed the geometry changed significantly when allowed to relax, thus reversing the interpretation. Mark and Herb Fischer also studied the interesting alternating geometries of carbodiimides with a sequential increase in the number of carbons in the chain. When John returned from England and saw the written manuscripts as chapters in Mark’s thesis, he wanted Mark to stay on for some additional months to do systematic geometry optimizations of dimers, trimers, etc. systematic studies being a hallmark of John’s research and subsequently Mark’s research as well. This delay created challenges for Warren Hehre and his wife Noko, who were waiting for Mark and Joan (Mark’s wife) to vacate their apartment and move on to a postdoc with Klaus Ruedenberg. Each week Warren would ask Mark when the apartment would be ready and Noko would ask Joan, saying that their spouse was the one who really wanted to knowassuming that Mark and Joan would not compare notes. When Mark first arrived in Ames, Iowa, for his postdoc, Klaus was focused on two students (Ernie Mehler and David Silver) who were trying to graduate and did not have as much time to devote to Mark. Since Mark is a self-starter, he was not content sitting around waiting for direction. Mark had brought the CNDO and INDO program with him to Ames. Walter England, a graduate student with Klaus, had written an orbital localization program, but they did not have a self-consistent field (SCF) program to produce the orbitals! So, Mark wrote the first SCF program at Ames by tying together parts of a Slater integral package for diatomics with pieces written by David Silver, Ernie Mehler, and Ralph Christopherson. Using his experiences with semiempirical codes, Mark wrote the SCF. Mark and Walter then put the localized orbital methods together with the SCF and wrote a paper on ab initio localized orbitals in diatomic orbitals. Interestingly, they were able to show that INDO and ab initio results agreed and that CNDO did not agree, due to its neglect of one-center exchange integrals. All told, Walter and Mark wrote seven papers on this theme. Mark learned similar lessons from John and Klaus that were unusual at the timeperhaps even today. Neither John nor Klaus insisted that their names be on papers that were from Mark’s independent work. In fact, they did not want their names on those papers, since they had not contributed to the work. In addition, they realized that you let really good people 2716
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graduate student, Theresa Windus. So, luck played a role in that Mark was at the right place at the right time. Mark’s comment was, “You have to grab the brass ring!” It was a huge change in the direction of his research. An equally important consequence of Mark’s year at the National Science Foundation arose from his frequent visits, together with Jan Jensen, to Walt Stevens and Mo Krauss at NIST. Out of these visits arose the eventual development of the effective fragment potential method that became a central component of the Gordon group research effort. In 1992, Mark moved to Iowa State University (ISU). This move also made a big impact on Mark’s research, since he now had access to many more graduate students to help advance his research. He has had great students at both NDSU and ISU, but the number of students really made a big difference. More students had heard more about ISU and would contact Mark for opportunities to work in the field. In addition to several students and postdocs who transitioned to ISU from NDSU (Paul Day, Jan Jensen, Nikita Matsunaga, Kiet Nguyen, Shujun Su, Keiko Takano, Theresa Windus), Mark was contacted by Simon Webb and Galina Chaban, who were interested in joining him at ISU. That was the beginning of the change to a larger research effort with many excellent students and postdocs. The late 1990s also saw the development of new collaborations and wonderful friendships in Australia. This began in 1998 with a brief sabbatical with Leo Radom, then at the Australian National University in Canberra. There, Mark also met and developed collaborations with Michael (Mick) Collins and Alistair Rendell. The interaction with Mick further developed Mark’s interests in dynamics. Mark and Alistair have a continuing collaboration in computational science that has been very fruitful. Mark continued to visit Leo in Australia regularly, and when Leo moved to Sydney and Peter Gill replaced him in Canberra, Mark and Peter developed a close friendship as well. On each of his trips to Australia, Mark was able to bring graduate students who had the opportunity to develop their own collaborations and to enjoy Australia. Mark has been and continues to be interested in developing methods that provide quantum mechanical accuracy with reduced computational cost. In 1996, Mark, together with Walt Stevens, Mo Krauss, David Garmer, students Jan Jensen and Simon Webb, postdoc Paul Day, Harold Basch, and Drora Cohen, published the first paper on the effective fragment potential (EFP) method, which was to become a major effort in the Gordon group. The initial work focused on placing water molecules around biomolecules that contain phosphorus. Mark and his group quickly added charge-transfer interactions and analytic gradients, so the positions of the water molecules could be optimized. As a consistent theme across his research, Mark tries to avoid empirical parameters as much as possible, so the EFP method is derived from first-principles with no fitted parameters, but with significant physical and chemical insight. Jan Jensen played a very important role in the early development of the EFP method. Subsequently, many excellent students and postdocs made, and continue to make, important contributions to the method. Numerous extensions to this method, including calculation of excitation energies and the prediction of nonlinear optical properties, have been developed over the years. Mark has also been active in developing the fragment molecular orbital (FMO) approach, initially developed by Kazuo Kitaura as an outgrowth of the Kitaura−Morokuma
interactions led to many beautiful collaborations that advanced silicon chemistry. In 1977, Mark received a letter from Kazuo Takatsuka who wanted to do a postdoc with Mark. He and his wife Kazuko became great friends with Mark and Joan, and Kazuo enjoyed his time working with Mark. Since the theoretical and computational chemistry community is tight-knit in Japan, word spread, and Mark subsequently had a sequence of excellent postdocs, including Satoshi Yabushita, Shogo Sakai, Shiro Koseki, Keiko Takano, and Takako Kudo. Both Keiko and Takako are now Vice Presidents at their respective universities, and Takako became the first female full professor at Gunma University. Mark has also had several visiting professors from Japan, including Kenichi Fukui, who shared the 1981 Nobel Prize in Chemistry with Roald Hoffmann. These interactions established many long-lived collaborations and resulted in many trips to Japan to visit his colleagues there and to enjoy the Japanese culture. Of course, Mark now enjoys many international collaborations. During the NDSU years, Mark had multiple undergraduate, graduate, and postdoctoral students. This is where Mark started to describe his students as belonging to either the “control” or “out-of-control” group. Among the early members of the outof-control group were Jerry Boatz, Thanh Truong, Tom Holme, and the instigator Kim (who me?) Baldridge. Mark has always enjoyed pranks and creativity, and there are way too many stories to tell of those days, but it was a great time of growth in his research. This was also the time when Mark hired Mike Schmidt, who would become a fixture in the group and one of the cornerstones for the development of the GAMESS software. Mark served as chairman of the chemistry department at NDSU from 1981 to 1989. The mid 1980s also saw the growth of a strong and lasting collaboration and friendship between Mark and Don Truhlar at the University of Minnesota. Mark and Don and their students worked together on the interfacing of electronic structure theory (GAMESS) and dynamics (POLYRATE). This very successful collaboration produced many joint publications and included a six-month sabbatical that Mark spent with Don in the Twin Cities during the winter of 1985−86. This was the winter of the great Thanksgiving snowstorm that dumped more than two feet of snow on the Twin Cities and pretty much shut everything down for two days. Mark’s parents, who were visiting from Florida, proudly wore the “I survived the Thanksgiving snowstorm” buttons that Joan made for them. Mark and Don remain good friends, and the electronic structure-dynamics interface remains an important component of Mark’s research. The next big influence in Mark’s career was in 1989−1990 when Mark spent a year as a rotator at the National Science Foundationthis was also during the time that Larry Davis was moving up from the Air Force Office of Scientific Research (AFOSR) to the Air Force Systems Command. Since Mark was in the Washington, DC, area, Larry asked Mark to help take care of the theory projects in AFOSR part-time, while they were looking for someone full-time. Mark was at Bolling Air Force Base a year later when Larry came in and said that Cal Tech had an Intel Touchstone Delta computer and asked if Mark wanted to parallelize GAMESS and run some calculations. Mark immediatelywithout blinking an eye or asking anyone elsesaid, “Absolutely!” This was how Mark got started in parallel computing. Of course, this endeavor would not have gotten off the ground were it not for an outstanding 2717
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honor to dedicate this special issue of The Journal of Physical Chemistry to him.
energy decomposition analysis and now carried on in Japan by former Gordon graduate student Dmitri Fedorov and in Ames by the Gordon group. The FMO method is one of several fragmentation approaches that have been gaining popularity in the past 15 years. Mark and current students and postdocs have worked closely with developers Kazuo Kitaura and Dmitri Fedorov to expand the FMO method and develop interfaces to the EFP method and with continuum solvation methods such as the polarizable continuum model (PCM). Mark’s postdoc Takeshi Nagata, now sadly deceased, worked on improved accuracy in the FMO gradients after he moved to Fedorov’s lab. The latest development is an integration of the EFP and FMO methods to form the effective fragment molecular orbital (EFMO) with collaborators Jan Jensen and his student Casper Steinmann and Mark’s recent graduate students Spencer Pruitt and Colleen Bertoni. One of the things that is attractive to Mark about the FMO method is that it scales extremely well with number of processors, which enables the highly parallel calculations that Mark loves. The march toward highly parallel computational chemistry was given a strong push when Mark was named the director of the Ames Laboratory Applied Mathematical and Computational Science (AMCS) program in 1997, a position he held until he resigned in 2014. The AMCS program included several highly talented computational scientists, including Brett Bode. David Halstead (sometimes known as Clusterman), Ricky Kendall, Masha Sosonkina, and David Turner, with ex officio members Bruce Harmon and Theresa Windus. This group of computer scientists and applied mathematicians played an important role in pushing computational science forward. Today, Mark still finds the areas of photochemistry and photobiology with dynamics as exciting areas of research both in theory development and application. Other areas of interest are condensed phase such as solvents, liquids (in particular, ionic liquids), interfacial molecular science, and heterogeneous catalysis. Of course, Mark is still very interested and active in the development of methods and algorithms for highperformance computing and new hardware architectures. Mark has many stories about every one of his students, postdocs, and collaborators, and we were only able to touch on a very few of them (mostly from the early days). So, we apologize if you were not recognized in any of these stories there is simply not enough space in this short forward to acknowledge everyone who has had an impact on Mark (and vice versa). Please see the lengthy list of former and current students, postdoctoral fellows, and visitors that accompanies this introduction to the “virtual special issue in honor of Mark Gordon” from The Journal of Physical Chemistry. A list of Mark’s more than 600 publications (including titles and coauthors) is also provided with this special issue. This list is regularly updated on the Gordon group website: http:// www.msg.chem.iastate.edu/publications/publications.html. Elsewhere on that website, one can find a 10-year-old photograph of the attendees at a conference in honor of Mark’s 65th birthday and an updated photo from this year’s 75th birthday symposium, which was organized to accompany this special issue. We thank all of those who contributed a paper to this issue, and all those who were able to attend the January 2017 conference. The fantastic response we received to the call for contributions to this issue shows what a remarkable impact Mark has had on the field and on the community. It is our
Theresa L. Windus Kim K. Baldridge Michael W. Schmidt Christine M. Aikens
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