Pablo Gaston Debenedetti, the Class of 1950 Professor in Engineering and Applied Science, professor of chemical and biological engineering, and a leading figure in the field of thermodynamics and statistical mechanics of liquids and glasses, transferred to emeritus status in the summer of 2024, after thirty-nine years on the Princeton faculty. 

In his tremendously successful research career, Pablo has worked in a range of related fields aiming to understand and predict the properties of liquids, solutions, crystals, and glasses. The common thread connecting these areas has been the use of thermodynamic principles, statistical mechanical theory, and rigorous molecular-based simulations.

Pablo has brought to bear upon Princeton’s overall research enterprise the same high standards and pioneering spirit that have informed his own scientific contributions. For more than twenty-five years, he has served in key leadership roles in which he has developed and supported the research and innovations of his colleagues, most notably as Princeton’s dean for research from 2013 to 2023. 

Born in Buenos Aires, Argentina, in 1953, Pablo received bilingual education in Spanish and English starting in primary school and learned Italian and French from his parents. He studied chemical engineering at the University of Buenos Aires and received his undergraduate degree in 1978. After a two-year period as a process and research engineer at an electrochemical company in Milan, Italy, he pursued graduate education at MIT, where he obtained master’s (1981) and Ph.D. (1985) degrees, also in chemical engineering. His doctoral research was on diffusion and mass transfer in supercritical fluids and was conducted under the supervision of Robert (Bob) Reid, a highly respected classical thermodynamicist. Pablo was appointed assistant professor in 1985 in what was then the Department of Chemical Engineering at Princeton and was promoted to associate professor in 1990, professor in 1994, and to his current named professorship in 1998.

Pablo has authored or coauthored more than 300 original research papers that are highly influential and heavily cited (Google Scholar, March 2024: 42,000 citations, h-index=98). His early work at Princeton focused on supercritical fluids. He subsequently developed an interest in metastable (supercooled) water and metastability more generally, which resulted in a series of seminal papers on the theory of metastability. 

His work on supercooled water included both theoretical and computational contributions. Specifically, he showed that water’s structural, dynamic, and thermodynamic anomalies constitute a cascade: they occur consecutively as the degree of order is increased. He used rigorous methods to demonstrate the existence of a liquid-liquid phase transition in supercooled water for several molecular models, which inspired major efforts to probe that transition experimentally that are now bearing fruit. He investigated hydration phenomena and hydrophobicity and provided clear answers to historical questions like the role of dewetting in hydrophobic attraction. He studied protein thermodynamics and folding transitions, including cold denaturation and the novel concept of low-temperature refolding. 

Pablo’s work on glasses and packings led to new tools for characterizing the energy landscapes and disorder in these systems, demonstrating the connection between dynamics and temperature-dependent changes in the sampling of these landscapes. He also worked on chiral symmetry breaking, a topic of interest for understanding the origins of life, studying the temporal evolution of simple models under broad ranges of initial conditions and model parameters, relevant to the emergence of biological homochirality. 

His many students, postdocs, and collaborators span the globe and continue to generate contributions following Pablo’s intellectual leadership. Many of them found their way to Princeton in June 2023 for an inspiring celebration of his seventieth birthday with a three-day scientific symposium. His impressive and rapidly expanding academic tree has eleven of his thirty-three Ph.D. students and eighteen out of twenty-seven supervised postdoctoral associates holding faculty positions and now training students of their own; other former students hold leading positions in industry and national laboratories.

Pablo’s work on metastability was his impetus for putting together a major research monograph, Metastable Liquids: Concepts and Principles, published by Princeton University Press in 1996. This book continues to be a “must read” reference for researchers in the field and has been cited many thousands of times in the research literature.

Pablo has also been an effective and influential teacher at both the graduate and undergraduate levels, primarily in the areas of thermodynamics and statistical mechanics. Despite being a highly demanding and rigorous instructor, he has always received very favorable reviews from his students. He was recognized with Princeton’s top teaching recognition, the President’s Award for Distinguished Teaching, in 2008.

Pablo’s command of organizational and leadership skills, and his desire to help his colleagues and the institution, led to a series of increasingly demanding administrative roles. To quote from his excellent autobiography that appeared in the Journal of Physical Chemistry B in 2023, “serving communities dedicated to the creation and transmission of knowledge has always been important and deeply satisfying.” He was an outstanding chair of the Department of Chemical Engineering from 1996 to 2004. He served as vice dean of the School of Engineering and Applied Science between 2008 and 2013, including a semester as acting dean. He was then selected as the University’s dean for research. In his ten years in that role, he made major investments in Princeton’s research enterprise, including new funds supporting innovation and exploratory research in all fields. He was also responsible for successfully steering the University’s research activities through the COVID-19 pandemic, including the safe and orderly closing and reopening of research laboratories. In collaboration with the Office of the Provost and the Office of the Dean of the Graduate School, he led the implementation of the matching research funds program (2016-22) and the elimination of graduate tuition from research grants.

Pablo’s research contributions have been widely recognized by a series of awards and honors. Among the most notable in that long list are election to the National Academy of Engineering, National Academy of Sciences, and American Academy of Arts and Sciences. He also received the Hildebrand Award from the American Chemical Society, several major awards from the American Institute of Chemical Engineers (Professional Progress, Walker, Institute Lecture, Alpha Chi Sigma), the Guggenheim Medal from the Institution of Chemical Engineers (United Kingdom), and the Aneesur Rahman Prize for Computational Physics from the American Physical Society.

Written by members of the Department of Chemical and Biological Engineering faculty.