Van Vleck, John

Van Vleck John Hasbrouck 331, 617 VohraYogeshK. 827 Volterra Vito 850 VoskoSyH. 592,611 Voss-Andreae Julian 43 Vracko Maijan 90,140... 

This book has been written in an attempt to provide students with the mathematical basis of chemistry and physics. Many of the subjects chosen are those that I wish that I had known when I was a student It was just at that time that the no-mans-land between these two domains - chemistry and physics - was established by the Harvard School , certainly attributable to E. Bright Wilson, Jr., J. H. van Vleck and the others of that epoch. I was most honored to have been a product, at least indirectly, of that group as a graduate student of J. C. Decius. Later, in my post-doc years. I profited from the Harvard-MIT seminars. During this experience I listened to, and tried to understand, the presentations by those most prestigious persons, who played a very important role in my development in chemistry and physics. The essential books at that time were most certainly the many publications by John C. Slater and the Bible on mathematical methods, by Margeneau and Murphy. They were my inspirations. 

In his 1933 paper on "tautomerism," Ingold began discussion with references to the physics of the electron, citing a 1923 paper by J. J. Thomson and a recent book by John H. Van Vleck.62 He noted Lewis s contributions (1923) to the notion of inductive effect ( ) in which electrons remain bound by their original atomic nuclei Lowry (1923) to the notion of electromeric effect, in which there is a displacement of a duplet, shifting from one pair of atoms to... 

Schweber and others have argued that quantum chemistry was a quintessentially American discipline, with Mulliken, Slater, Van Vleck, Urey, Pauling, Edward Condon, Oppenheimer, Ralph Kronig, I. I. Rabi, Clarence Zener, David Dennison, Philip M. Morse, Eyring, John G. Kirkwood, George E. 

See Mulliken, Life, 136 and S. S. Schweber, "Shelter Island, Pocono, and Oldstone The Emergence of American Quantum Electrodynamics after World War II," Osiris, 2d ser., 2 (1986) 265302, on 277. John Van Vleck was present (279). 

Van Vleck and Sherman, quoted in Schweber, "Young John Clarke Slater," 404405. 

Crystal field theory has its origins in Hans Bethe s famous 1929 paper Splitting of terms in crystals. In that paper Bethe demonstrated what happens to the various states of an ion when it is placed in a crystalline environment of definite symmetry. Later, John Van Vleck showed that the results of that investigation would apply equally well to a transition-metal compound if it could be approximated as a metal ion surrounded by ligands which only interact electrostatically with the... 

Huzinaga was the recipient of the 1994 John C. Polanyi Award of the Canadian Society for Chemistry. In his award lecture he described his model potential method, which deals only with the active electrons in molecular and solid state calculations. An invited review article,59 based on his 1994 Polanyi Award lecture, chronicles his efforts to develop a sound theoretical framework for the core-valence separation of electrons, a problem Van Vleck and Sherman60 once referred to as the nightmare of the inner core. ... 

John Hasbrouck Van Vleck (1899-1980). 13Paul Victor Henri Pascal (1880-1968). 

John H. Van Vleck and R. Finkelstein First application of electrostatic model to absorption bands of the ruby... 

Soon after the development of the quantum mechanical model of the atom, physicists such as John H. van Vleck (1928) began to investigate a wave-mechanical concept of the chemical bond. The electronic theories of valency, polarity, quantum numbers, and electron distributions in atoms were described, and the valence bond approximation, which depicts covalent bonding in molecules, was built upon these principles. In 1939, Linus Pauling s Nature of the Chemical Bond offered valence bond theory (VBT) as a plausible explanation for bonding in transition metal complexes. His application of VBT to transition metal complexes was supported by Bjerrum s work on stability that suggested electrostatics alone could not account for all bonding characteristics. 

In 1951, chemists trying to make sense of metal complex optical spectra and color returned to an emphasis on the ionic nature of the coordinate covalent bond. Coordination chemists rediscovered physicists Hans Bethe s and John van Vleck s crystal field theory (CFT),... 

Philip W. Anderson, Sir NevUl F. Mott, John H. van Vleck 1922 Niels Bohr... 

Most of the transition metal oxides and salts may be treated as ionic crystals. The valence electrons of s symmetry (4s, 5s, or 6s) are stripped off. The metal forms an ion that is considerably smaller than the atom. The inner (n - l)d electrons (3d, 4d, or 5d) are degenerate in the central field approximation of the atom. In the next step, multiplets are formed (Section 2.4). In the third step, the transition metal ions interact with the crystal field, which is dominated by repulsion from the neighboring negative ions. This leads to a splitting of the 3d orbital energies. The theory describing the splitting of the electronic states in a crystal field is due to the American physicists Hans Bethe and John van Vleck and is called crystal field theory (CFT). 

With the Pauli principle, it became possible to comprehend "valence" saturation It seemed reasonable to suppose that whenever two electrons of different atoms combine to form a symmetric Schrodinger vibration, a bond will result. As it will be repeatedly argued in the work of both Heitler and London, spin would become one of the most significant indicators of valence behavior and would forever be in the words of John Hasbrouck Van Vleck (a physicist from Harvard) "at the heart of chemistry" (Van Vleck 1970, 240). 

John Hasbrouck Van Vleck (1899-1980) attended the University of Wisconsin from 1916 to 1920 and a summer school in Chicago in 1920 where he met Mulliken for... 

Nobel prize for Physics John Bardeen, Leon N. Cooper and J. Robert Schrieffer, for their jointly developed theory of superconductivity, usually called the BCS theory. 1977 Nobel prize for Physics Philip W. Anderson, Sir Nevill F. Mott and John H. van Vleck, for their fundamental theoretical investigations of the electronic structure of magnetic and disordered systems. 

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