Robert Walter Zwanzig (born Brooklyn, New York, 9 April 1928 – died Bethesda, Maryland, May 15, 2014) was an American theoretical physicist and chemist who made important contributions to the statistical mechanics of irreversible processes, protein folding, and the theory of liquids and gases.

Background

Zwanzig received his bachelor's degree from Brooklyn Polytechnic Institute in 1948 and his master's degree from 1950 at the University of Southern California. In 1952 he completed a doctorate in physical chemistry at Caltech under the supervision of

John G. Kirkwood John "Jack" Gamble Kirkwood (May 30, 1907, Gotebo, Oklahoma – August 9, 1959, New Haven, Connecticut) was a noted chemist and physicist, holding faculty positions at Cornell University, the University of Chicago, California Institute of Techno ...

. His thesis title was ''Quantum Hydrodynamics: a statistical mechanical theory of light scattering from simple non-polar fluids''. From 1951 to 1954 he worked as a post-doctoral researcher in theoretical chemistry at Yale University, and from 1954 to 1958 he was an assistant professor in chemistry at Johns Hopkins University. From 1958 to 1966 he was a physical chemist at the National Bureau of Standards and from 1966 to 1979 he was a research professor at the Institute for Physical Science and Technology of the University of Maryland, where until 1988 he held he title of Distinguished Professor. From 1974 - 75 he was a Fairchild Scholar at Caltech. From 1988 onwards he was a researcher at the National Institutes of Health (National Institute of Diabetes and Digestive and Kidney Diseases) in Bethesda, Maryland, where he was a Fogarty Scholar (1987–88) and later worked as a research scientist emeritus. One of his early works from 1954 is often cited as the first use of free energy perturbation theory, and the resulting equation for the change in free energy is sometimes referred to as the "Zwanzig equation". In the early 1960s he wrote some now classic works on the non-equilibrium thermodynamics and statistical mechanics of irreversible processes. He developed the projection operator formalism, which made it possible to derive irreversible transport equations (such as the Boltzmann equation and other master equations) from reversible microscopic quantum mechanical dynamic equations. He drew heavily from the work of Leon van Hove. The projection operator formalism later found wide application and is now known as the Zwanzig-Mori formalism (also named after

Hazime Mori is the Japanese word meaning . In the Japanese traditional martial arts such as karate, judo, aikido, Kūdō and kendo, it is a verbal command to "begin". Hajime is also a common Japanese given name for males. In the Amami Islands, Hajime (元) i ...

, who published similar results in 1965). An important result of the Zwanzig-Mori formalism, the Nakajima-Zwanzig equation, bears his name and reflects the important contributions of Sadao Nakajima made around the same time. Together with Tsu-Wei Nee he derived a theory for the dielectric function and

dielectric friction In electromagnetism, a dielectric (or dielectric medium) is an Insulator (electricity), electrical insulator that can be Polarisability, polarised by an applied electric field. When a dielectric material is placed in an electric field, electr ...

of dipolar liquids based on an extension of Lars Onsager's work. Later he worked on the

protein folding problem Protein structure prediction is the inference of the three-dimensional structure of a protein from its amino acid sequence—that is, the prediction of its secondary and tertiary structure from primary structure. Structure prediction is different ...

among other things.

Awards and honors

He received many awards, including * the Peter Debye Award (1976), * the

Irving Langmuir Award The Irving Langmuir Prize in Chemical Physics is awarded annually, in even years by the American Chemical Society and in odd years by the American Physical Society. The award is meant to recognize and encourage outstanding interdisciplinary researc ...

(1985), * the Joel H. Hildebrand Award (1994). He was a Fellow of the

National Academy of Sciences The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nati ...

and the American Chemical Society.

Selected bibliography

*'' Nonequilibrium Statistical Mechanics'', Oxford University Press 2001

References

External links

Obituary from the University of Maryland
{{DEFAULTSORT:Zwanzig, Robert 1928 births 2014 deaths American physicists American physical chemists University of Southern California alumni Polytechnic Institute of New York University alumni California Institute of Technology alumni University of Maryland, College Park faculty