Walter Kohn
Encyclopedia
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
n-born American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
theoretical physicist.
He was awarded, with John Pople
John Pople
Sir John Anthony Pople, KBE, FRS, was a Nobel-Prize winning theoretical chemist. Born in Burnham-on-Sea, Somerset, England, he attended Bristol Grammar School. He won a scholarship to Trinity College, Cambridge in 1943. He received his B. A. in 1946. Between 1945 and 1947 he worked at the Bristol...
, the Nobel Prize in chemistry
Nobel Prize in Chemistry
The Nobel Prize in Chemistry is awarded annually by the Royal Swedish Academy of Sciences to scientists in the various fields of chemistry. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in chemistry, physics, literature,...
in 1998. The award recognized their contributions to the understandings of the electronic properties of materials. In particular, Kohn played the leading role in the development of density functional theory
Density functional theory
Density functional theory is a quantum mechanical modelling method used in physics and chemistry to investigate the electronic structure of many-body systems, in particular atoms, molecules, and the condensed phases. With this theory, the properties of a many-electron system can be determined by...
, which made it possible to incorporate quantum mechanical effects in the electronic density
Electronic density
In quantum mechanics, and in particular quantum chemistry, the electronic density is a measure of the probability of an electron occupying an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typically denoted as either...
(rather than through its many-body wavefunction
Wavefunction
Not to be confused with the related concept of the Wave equationA wave function or wavefunction is a probability amplitude in quantum mechanics describing the quantum state of a particle and how it behaves. Typically, its values are complex numbers and, for a single particle, it is a function of...
). This computational simplification led to many insights and became an essential tool for electronic materials, atomic and molecular structure.
Early years in Canada
Kohn arrived in EnglandEngland
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
as part of the famous Kindertransport
Kindertransport
Kindertransport is the name given to the rescue mission that took place nine months prior to the outbreak of the Second World War. The United Kingdom took in nearly 10,000 predominantly Jewish children from Nazi Germany, Austria, Czechoslovakia, Poland and the Free City of Danzig...
rescue operation, immediately after the annexation
Annexation
Annexation is the de jure incorporation of some territory into another geo-political entity . Usually, it is implied that the territory and population being annexed is the smaller, more peripheral, and weaker of the two merging entities, barring physical size...
of Austria
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
by Hitler
Adolf Hitler
Adolf Hitler was an Austrian-born German politician and the leader of the National Socialist German Workers Party , commonly referred to as the Nazi Party). He was Chancellor of Germany from 1933 to 1945, and head of state from 1934 to 1945...
. He is from a Jewish family, both of his parents were later killed in the Holocaust. Because he was a German national, he was sent to Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
by the English in July 1940. As a 17-year-old, Kohn traveled as part of a British convoy moving through U-boat-infested waters to Quebec City
Quebec City
Quebec , also Québec, Quebec City or Québec City is the capital of the Canadian province of Quebec and is located within the Capitale-Nationale region. It is the second most populous city in Quebec after Montreal, which is about to the southwest...
in Canada; and from there, by train, to a camp in Trois-Rivières
Trois-Rivières
Trois-Rivières means three rivers in French and may refer to:in Canada*Trois-Rivières, the largest city in the Mauricie region of Quebec, Canada*Circuit Trois-Rivières, a racetrack in Trois-Rivières, Quebec...
. He was at first held in detention in a camp near Sherbrooke, Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
. This camp, as well as others, provided a small number of educational facilities that Kohn used to the fullest, and he finally succeeded in entering the University of Toronto. As a German national, the future Nobel laureate in chemistry was not allowed to enter the chemistry building, and so he opted for physics and mathematics. A short but fascinating autobiography may be found on the Nobelist webpage.
Scientific career
Kohn received a war-time bachelor's degree in applied mathematics at the end of his one-year army service, having completed only 2½ out of the 4-year undergraduate program, from the University of TorontoUniversity of Toronto
The University of Toronto is a public research university in Toronto, Ontario, Canada, situated on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in Upper Canada...
in 1945; he was awarded an M.A. degree in applied mathematics by Toronto in 1946. Kohn was awarded a Ph.D. degree in physics by Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
in 1948, where he worked under Julian Schwinger
Julian Schwinger
Julian Seymour Schwinger was an American theoretical physicist. He is best known for his work on the theory of quantum electrodynamics, in particular for developing a relativistically invariant perturbation theory, and for renormalizing QED to one loop order.Schwinger is recognized as one of the...
on the three-body scattering problem. At Harvard he also fell under the influence of Van Vleck
Van Vleck
Van Vleck can refer to:people*John Monroe Van Vleck, American astronomer, father of Edward Burr van Vleck*Edward Burr Van Vleck, American mathematician, father of John Hasbrouck van Vleck, son of John Monroe van Vleck...
and solid state physics.
He moved from Harvard to Carnegie Mellon University
Carnegie Mellon University
Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....
from 1950 to 1960, after a short stint in Copenhagen as a National Research Council of Canada
National Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
post-doctoral fellow. At Carnegie Mellon he did much of his seminal work on multiple-scattering band-structure work, now known as the KKR method. His association with Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
got him involved with semiconductor physics, and produced a long and fruitful collaboration with Luttinger
Joaquin Mazdak Luttinger
Joaquin Mazdak Luttinger was an American physicist well-known for his contributions to the theory of interacting electrons in one-dimensional metals and the Fermi-liquid theory...
(including, for example, development of the Luttinger-Kohn model
K·p perturbation theory
In solid-state physics, k·p perturbation theory is an approximation scheme for calculating the band structure and optical properties of crystalline solids. It is pronounced "k dot p", and is also called the "k·p method"...
of semiconductor band structure). In 1960 he moved to the newly founded University of California, San Diego
University of California, San Diego
The University of California, San Diego, commonly known as UCSD or UC San Diego, is a public research university located in the La Jolla neighborhood of San Diego, California, United States...
, held a term as the physics department chair, and remained until 1979. He then accepted the Founding Director's position at the new Institute for Theoretical Physics in Santa Barbara. He took his present position as a professor in the Physics Department
UC Santa Barbara Physics Department
The Physics Department at the University of California, Santa Barbara has 58 faculty members. It offers academic programs leading to the B.A., B.S., and Ph.D. degrees.-Faculty Awards:...
at the University of California at Santa Barbara in 1984; he is currently professor emeritus and research professor.
Kohn made significant contributions to semiconductor physics, which led to his award of the Oliver E. Buckley Prize
Buckley Prize
The Oliver E. Buckley Condensed Matter Prize is an annual award given by the American Physical Society "to recognize and encourage outstanding theoretical or experimental contributions to condensed matter physics." It was endowed by AT&T Bell Laboratories as a means of recognizing outstanding...
by the American Physical Society
American Physical Society
The American Physical Society is the world's second largest organization of physicists, behind the Deutsche Physikalische Gesellschaft. The Society publishes more than a dozen scientific journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than 20...
. He was also awarded the Feenburg medal for his contributions to the many-body problem
Many-body problem
The many-body problem is a general name for a vast category of physical problems pertaining to the properties of microscopic systems made of a large number of interacting particles. Microscopic here implies that quantum mechanics has to be used to provide an accurate description of the system...
.
His work on density functional theory was initiated during a visit to the École Normale Supérieure
École Normale Supérieure
The École normale supérieure is one of the most prestigious French grandes écoles...
in Paris, with Pierre Hohenberg
Pierre Hohenberg
Pierre C. Hohenberg is a French-American theoretical physicist, who works primarily on statistical mechanics....
, and was prompted by a consideration of alloy theory. The
Hohenberg-Kohn theorem was further developed, in collaboration with Lu Sham, to produce the Kohn-Sham equations. The latter is the standard work horse of modern materials science, and even used in quantum theories of plasmas.
In 2004, a study of all citations to the Physical Review journals from 1893 until 2003, found Kohn to be an author of five of the 100 papers with the "highest citation impact", including the first two.
Scientist with a great following
Walter Kohn is a well-known and much-loved figure on many European campuses. He was aregular visitor to Jacques Friedel's laboratory and Carl Moser's laboratory (CECAM)
in Orsay, Universite Paris IX. Another favorite stop for Kohn is in Switzerland, at the
ETH
Eth
Eth is a letter used in Old English, Icelandic, Faroese , and Elfdalian. It was also used in Scandinavia during the Middle Ages, but was subsequently replaced with dh and later d. The capital eth resembles a D with a line through the vertical stroke...
. He also visits the National Research Council of Canada
National Research Council of Canada
The National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
, his Canadian Alma Mater
the University of Toronto
University of Toronto
The University of Toronto is a public research university in Toronto, Ontario, Canada, situated on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution of higher learning in Upper Canada...
, Montreal, and Sherbrooke whenever his itineraries permit him to do so. He is equally at home in Denmark, Israel, England or France. He has students in virtually every part of the world.
In 1957, he relinquished his Canadian citizenship and became a naturalized citizen of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
He is a member of the International Academy of Quantum Molecular Science
International Academy of Quantum Molecular Science
The International Academy of Quantum Molecular Science is an international scientific learned society covering all applications of quantum theory to chemistry and chemical physics. It was created in Menton in 1967. The founding members were Raymond Daudel, Per-Olov Löwdin, Robert G. Parr, John...
.
See also
- List of Jewish Nobel laureates
- List of Nobel laureates affiliated with the University of California, Santa Barbara
Some publications
- W. Kohn, An essay on condensed matter physics in the twentieth century, Reviews of Modern Physics, Vol. 71, No. 2, pp. S59-S77, Centenary 1999. APS
- W. Kohn, Nobel Lecture: Electronic structure of matter — wave functions and density functionals, Reviews of Modern Physics, Vol. 71, No. 5, pp. 1253–1266 (1999). APS
- D. Jérome, T.M. Rice, and W. Kohn, Excitonic Insulator, Physical Review, Vol. 158, No. 2, pp. 462–475 (1967). APS
- P. Hohenberg, and W. Kohn, Inhomogeneous Electron Gas, Physical Review, Vol. 136, No. 3B, pp. B864-B871 (1964). APS
- W. Kohn, and L. J. Sham, Self-Consistent Equations Including Exchange and Correlation Effects, Physical Review, Vol. 140, No. 4A, pp. A1133-A1138 (1965). APS
- W. Kohn, and J. M. Luttinger, New Mechanism for Superconductivity, Physical Review Letters, Vol. 15, No. 12, pp. 524–526 (1965). APS
- W. Kohn, Theory of the Insulating State, Physical review, Vol. 133, No. 1A, pp. A171-A181 (1964). APS
- W. Kohn, Cyclotron Resonance and de Haas-van Alphen Oscillations of an Interacting Electron Gas, Physical Review, Vol. 123, pp. 1242–1244 (1961). APS
External links
- Photograph of Walter Kohn: http://www.badw.de/aktuell/pressemitteilungen/2003/PM_11_2003/kohn2003.jpg
- "Quantum Chemistry Comes of Age," The Chemical Educator, Vol. 5, No. 3, S1430-4171(99)06333-7, DOI: 10.1007/s00897990333a, © 2000 Springer-Verlag New York, Inc.
- Freeview video interview with Walter Kohn by the Vega Science Trust
- Official homepage of the Nobel Prize in Chemistry in 1998
- Kohn's faculty website at University of California-Santa Barbara. Retrieved November 11, 2006.
