Robert W. Zwanzig

Robert W. Zwanzig, 86, Distinguished University Professor Emeritus at the University of Maryland and scientist emeritus at the National Institute of Diabetes & Digestive & Kidney Diseases

(NIDDK), died on May 15 in Bethesda, Md.

Born in Brooklyn, Zwanzig earned a B.S. in chemistry at Polytechnic Institute of Brooklyn (now New York University Polytechnic School of Engineering) in 1948, an M.S. in chemistry at the University of Southern California in 1950, and a Ph.D. in physical chemistry at the California Institute of Technology in 1952.

He was an assistant professor of chemistry at Johns Hopkins University from 1954 until 1958, when he joined the staff of the National Bureau of Standards (now the National Institute of Standards & Technology).

Zwanzig joined the Institute of Physical Science & Technology at the University of Maryland in 1966. Then in 1988, he served as chief of the section on theoretical biophysics in the Laboratory of Chemical Physics in NIDDK, a role he held until his retirement in 2004.

An expert in the field of statistical mechanics, Zwanzig produced numerous fundamental articles and the book “Nonequilibrium Statistical Mechanics,” based on his research. He developed a mathematical projection operator technique that has been a cornerstone of the study of irreversible processes. In addition, he introduced perturbation theory as a route to obtain thermodynamic properties of gases and liquids.

He was an emeritus member of ACS, joining in 1952 and receiving three of its awards: the Peter Debye Award in Physical Chemistry in 1976, the Irving Langmuir Award in Chemical Physics in 1984, and the Joel Henry Hildebrand Award in the Theoretical & Experimental Chemistry of Liquids in 1994. He was a fellow of the American Association for the Advancement of Science and a member of the National Academy of Sciences.

He enjoyed baking bread and made-from-scratch pizza and making dry martinis and hearty soups. He was also an ice dancer and enjoyed walking the towpath along the Chesapeake and Ohio Canal.

He is survived by Frances, his wife of 60 years; his daughter, Elizabeth Bennett; and his son, Carl.