Marshall Fixman

We sadly report the passing of Professor Marshall Fixman on February 27, 2016 in Loveland, Colorado. Marshall was a man of extraordinary talent and contributions to science. His achievements were recognized by his election to the National Academy of Sciences in 1973. Marshall Fixman is survived by his daughter Susan and son Andrew. His wife of 41 years, Professor Branka Ladanyi, predeceased Marshall by less than a month, and his daughter, Laura, in 2015.

Marshall earned the bachelor’s degree from Washington University in Saint Louis and then proceeded to the Massachusetts Institute of Technology, where he worked with Walter Stockmayer. During his graduate study Marshall used the cluster expansion method to derive the perturbation expansion for the single polymer chain radius of gyration. His results showed that for long polymer chains the excluded volume cannot be treated perturbatively, thus signaling the need for a renormalization group approach. After receiving the PhD, Marshall went to Yale to work with John Kirkwood as a postdoctoral fellow. There, he developed a molecular level theory of Rayleigh scattering by a simple fluid. At that time many expected that Einstein’s macroscopic fluctuation theory was incorrect, but Marshall’s microscopic analysis agreed fully with Einstein’s result.

At this point, the US Army intervened in Marshall’s career; he spent most of his service time at the Rocky Mountain Arsenal, near Denver, Colorado. While in the army, Marshall found time to develop his thoughts about the theory of liquids. In 1956 he returned to the East Coast as an instructor at Harvard and then spent a couple of years at the Mellon Institute, then under the stimulating scientific leadership of Paul Flory. Based on his extraordinary talent, he moved directly into a full professor position in the Department of Chemistry at the University of Oregon in Eugene, where he would also head the newly created Institute of Theoretical Science. At Oregon, Marshall formulated a novel approach to the transport properties of fluids near their critical points. His approach, reformulated later by Kawasaki and by Kadanoff and Swift, became known as the mode-coupling theory. A descendent of this theory is still being used today to describe the dynamics of glass-forming fluids.

Next, the East Coast called back. Marshall spent a sabbatical at Harvard and then moved to Yale. There, together with his student Jeffrey Skolnick, Marshall developed a theory for the electrostatic persistence length of polyelectrolytes. Their work is the core of the Odijk-Skolnick-Fixman theory, which is still being used today. At this time Marshall also developed a theory for diffusion-controlled reactions, together with another student, Gerald Wilemski.

In 1979, Marshall moved his family West again; he and his wife Branka joined the faculty in the Department of Chemistry at Colorado State University. The move spurred another dimension to Marshall’s career where he became occupied with simulational studies of polymeric fluids. Marshall was one of the pioneers of this field and he developed many novel simulation methods that allowed him to study relatively long chains on what is considered now very slow computers. One of his last projects concerned the nature of the stress in a polymer liquid. Using computer simulations Marshall established that the commonly used assumption of the intramolecular origin of the stress is incorrect. The same result was independently obtained by other simulators at about the same time. In recognition of his deep and important scientific contributions, Marshall earned the title University Distinguished Professor, one of the highest honors bestowed by Colorado State University.

Marshall’s work was well recognized in the scientific community. Over the course of his career, he received major awards including the American Chemical Society Award in Pure Chemistry (1964), the American Physical Society High Polymer Physics Prize (1980), and the American Chemical Society Award in Polymer Chemistry (1991). He was elected a fellow of American Physical Society (1962), the American Academy of Arts and Sciences (1973) and the National Academy of Sciences (1973).

In addition to his tremendous contributions to science, Marshall had other passions including hiking in the mountains and photography. Over many decades of his life he scaled mountains across North America and Europe. He left behind many Tbyte drives filled with high resolution photos either scanned from film and slides or taken more recently with digital equipment. In a recent conversation, Marshall bemoaned the fact that he had always imagined that when he retired he would traipse the world carrying a large camera to record his forays only to find himself too weak to carry such a camera. To his death, he was engaged and interested in the world around him. He reveled in the detection of gravitational waves that happened a couple of weeks before his death. He was passionate about politics and eternally analytical and practical.

Through his personal interactions and writings, he taught and inspired several generations of theoretical physical chemists. He continually expanded and improved physical theories and mathematical techniques. With his passing, we lose a man of tremendous intellect, practicality and grace.