Van Vleck, John Hasbrouck, 1899–1980, American physicist, b. Middletown, Conn., Ph.D. Harvard, 1922. As a professor at Harvard, Van Vleck developed fundamental theories on the quantum mechanics of magnetism and on molecular bonding (ligand field theory). For his contributions to the understanding of electrons in magnetic, noncrystalline solids, Van Vleck was awarded the 1977 Nobel Prize in Physics, along with Philip W. Anderson and Sir Nevill Mott.
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