John Hasbrouck van Vleck (March 13, 1899 – October 27, 1980) was an American physicist. Born in Middletown, Connecticut, and growing up in Madison, Wisconsin, he went to Harvard for college and graduate school. He joined the University of Minnesota as an assistant professor in 1923, then moved to the University of Wisconsin before settling at Harvard. Van Vleck developed fundamental theories of the quantum mechanics of magnetism and the bonding in metal complexes (crystal field theory).

Vleck participated in the Manhattan Project by serving on the Los Alamos Review committee in 1943. The committee, established by General Leslie Groves, also consisted of W.K. Lewis of MIT, Chairman; E.L. Rose, of Jones & Lamson; E.B. Wilson of Harvard; and Richard C. Tolman, Vice Chairman of NDRC. The committee's important contribution (originating with Rose) was a reduction in the size of the firing gun for the Thin Man bomb. This concept eliminated additional design-weight and sped up production of the bomb for its eventual release over Hiroshima. Source: Now It Can Be Told, Leslie R. Groves, Lieutenant General, U.S. Army, Retired, Harper & Brothers Publishers, 1962, First Edition, LIB Catalog Card No. 61-10208, Pages 162-63.

In the year 1961-62 he was George Eastman Visiting Professor in the University of Oxford and Professorial Fellow of Balliol College. He was awarded the Lorentz Medal in 1974. For his contributions to the understanding of electrons in non-crystalline magnetic solids, van Vleck was awarded the 1977 Nobel Prize in Physics, along with Philip W. Anderson and Sir Nevill Mott

Van Vleck transformations are also named after him.

Links

• John Hasbrouck van Vleck
  
• Autobiography
  
• On the verge of Umdeutung in Minnesota: Van Vleck and the correspondence principal; Duncan and Janssen, Elsevier Science, University of Pittsburg archive - http://philsci-archive.pitt.edu/archive/00002818/01/duncan-janssen.pdf