Walter Kohn (; March 9, 1923 – April 19, 2016) was an Austrian-American

theoretical physicist Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experime ...

and

theoretical chemist Theoretical chemistry is the branch of chemistry which develops theoretical generalizations that are part of the theoretical arsenal of modern chemistry: for example, the concepts of chemical bonding, chemical reaction, valence, the surface ...

. He was awarded, with

John Pople Sir John Anthony Pople (31 October 1925 – 15 March 2004) was a British theoretical chemist who was awarded the Nobel Prize in Chemistry with Walter Kohn in 1998 for his development of computational methods in quantum chemistry. Early ...

, the

Nobel Prize in Chemistry ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then "M ...

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 (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body ...

, which made it possible to calculate

quantum mechanical Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, qua ...

electronic structure by equations involving the

electronic density In quantum chemistry, electron density or electronic density is the measure of the probability of an electron being present at an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial va ...

(rather than the many-body

wavefunction A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude, and the probabilities for the possible results of measurements ...

). This computational simplification led to more accurate calculations on complex systems as well as many new insights, and it has become an essential tool for materials science, condensed-phase physics, and the chemical physics of atoms and molecules.

Early years in Canada

Kohn arrived in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

as part of the

Kindertransport The ''Kindertransport'' (German for "children's transport") was an organised rescue effort of children (but not their parents) from Nazi-controlled territory that took place during the nine months prior to the outbreak of the Second World ...

rescue operation immediately after the

annexation Annexation (Latin ''ad'', to, and ''nexus'', joining), in international law, is the forcible acquisition of one state's territory by another state, usually following military occupation of the territory. It is generally held to be an illegal act ...

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

Hitler Adolf Hitler (; 20 April 188930 April 1945) was an Austrian-born German politician who was dictator of Nazi Germany, Germany from 1933 until Death of Adolf Hitler, his death in 1945. Adolf Hitler's rise to power, He rose to power as the le ...

. He was from a

Jewish Jews ( he, יְהוּדִים, , ) or Jewish people are an ethnoreligious group and nation originating from the Israelites Israelite origins and kingdom: "The first act in the long drama of Jewish history is the age of the Israelites""The ...

family, and has written, "My feelings towards Austria, my native land, are – and will remain – very painful. They are dominated by my vivid recollections of 1 1/2 years as a Jewish boy under the

Nazi Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in ...

regime, and by the subsequent murder of my parents, Salomon and Gittel Kohn, of other relatives and several teachers, during the

Holocaust The Holocaust, also known as the Shoah, was the genocide of European Jews during World War II. Between 1941 and 1945, Nazi Germany and its collaborators systematically murdered some six million Jews across German-occupied Europe; a ...

. ... I want to mention that I have a strong Jewish identity and – over the years – have been involved in several Jewish projects, such as the establishment of a strong program of Judaic Studies at the University of California in San Diego.". Kohn also has identified as

Deist Deism ( or ; derived from the Latin '' deus'', meaning "god") is the philosophical position and rationalistic theology that generally rejects revelation as a source of divine knowledge, and asserts that empirical reason and observation ...

. Because he was an Austrian national, he was transferred to

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

in July 1940 after the outbreak of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. As a 17-year-old, Kohn traveled as part of a British convoy moving through U-boat-infested waters to

Quebec City Quebec City ( or ; french: Ville de Québec), officially Québec (), is the capital city of the Provinces and territories of Canada, Canadian province of Quebec. As of July 2021, the city had a population of 549,459, and the Communauté métrop ...

in Canada; and from there, by train, to a camp in

Trois-Rivières Trois-Rivières (, – 'Three Rivers') is a city in the Mauricie administrative region of Quebec, Canada, at the confluence of the Saint-Maurice and Saint Lawrence rivers, on the north shore of the Saint Lawrence River across from the city of ...

. He was at first held in detention in a camp near

Sherbrooke Sherbrooke ( ; ) is a city in southern Quebec, Canada. It is at the confluence of the Saint-François and Magog rivers in the heart of the Estrie administrative region. Sherbrooke is also the name of a territory equivalent to a regional cou ...

Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...

. 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.

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 Toronto The University of Toronto (UToronto or U of T) is a public research university in Toronto, Ontario, Canada, located on the grounds that surround Queen's Park. It was founded by royal charter in 1827 as King's College, the first institution ...

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 is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

in 1948, where he worked under

Julian Schwinger Julian Seymour Schwinger (; February 12, 1918 – July 16, 1994) was a Nobel Prize winning American theoretical physicist. He is best known for his work on quantum electrodynamics (QED), in particular for developing a relativistically invariant ...

on the three-body scattering problem. At Harvard he also fell under the influence of Van Vleck and solid state physics. He moved from Harvard to Carnegie Mellon University from 1950 to 1960, after a short stint in Copenhagen as a

National Research Council of Canada The National Research Council Canada (NRC; french: Conseil national de recherches Canada) is the primary national agency of the Government of Canada dedicated to science and technology research & development. It is the largest federal research ...

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 Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial Research and development, research and scientific developm ...

got him involved with semiconductor physics, and produced a long and fruitful collaboration with Luttinger (including, for example, development of the Luttinger-Kohn model of semiconductor

band structure In solid-state physics, the electronic band structure (or simply band structure) of a solid describes the range of energy levels that electrons may have within it, as well as the ranges of energy that they may not have (called ''band gaps'' or ' ...

). In 1960 he moved to the newly founded

University of California, San Diego The University of California, San Diego (UC San Diego or colloquially, UCSD) is a public university, public Land-grant university, land-grant research university in San Diego, California. Established in 1960 near the pre-existing Scripps Insti ...

, held a term as the physics department chair, and remained until 1979. It was during this period, he, along with his student

Chanchal Kumar Majumdar Chanchal Kumar Majumdar () (11 August 1938 – 20 June 2000) was an Indian condensed matter physicist and the founder director of S.N. Bose National Centre for Basic Sciences. Known for his research in quantum mechanics, Majumdar was an electe ...

developed the ''Kohn–Majumdar theorem'' related to

Fermi gas An ideal Fermi gas is a state of matter which is an ensemble of many non-interacting fermions. Fermions are particles that obey Fermi–Dirac statistics, like electrons, protons, and neutrons, and, in general, particles with half-integer sp ...

and its bound and unbound states. He then accepted the Founding Director's position at the new Institute for Theoretical Physics in Santa Barbara. He took his position as a professor in the Physics Department at the

University of California at Santa Barbara The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a public land-grant research university in Santa Barbara, California with 23,196 undergraduates and 2,983 graduate students enrolled in 2021–2022. It is part of the U ...

in 1984; where he worked until the end of his life. Kohn made significant contributions to semiconductor physics, which led to his award of the Oliver E. Buckley Prize by the American Physical Society. He was also awarded the Feenburg medal for his contributions to the

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 many interacting particles. ''Microscopic'' here implies that quantum mechanics has to be used to provid ...

. His work on density functional theory was initiated during a visit to the

École Normale Supérieure École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, S ...

in Paris, with

Pierre Hohenberg Pierre C. Hohenberg (3 October 1934 – 15 December 2017) was a French-American theoretical physicist, who worked primarily on statistical mechanics. Hohenberg studied at Harvard, where he earned his bachelor's degree in 1956 and a master's degr ...

, and was prompted by a consideration of alloy theory. The

Hohenberg–Kohn theorem Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body ...

was further developed, in collaboration with

Lu Jeu Sham Lu Jeu Sham ( Chinese: 沈呂九) (born April 28, 1938) is an American physicist. He is best known for his work with Walter Kohn on the Kohn–Sham equations. Biography Lu Jeu Sham's family was from Fuzhou, Fujian, but he was born in British Hon ...

, to produce the Kohn-Sham equations. The latter is the standard work horse of modern materials science,E. K. U. Gross and R. M. Dreizler, ''Density Functional Theory'', Plenum 1993 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. Walter Kohn Oxford University

In 1957, he relinquished his Canadian citizenship and became a

naturalized citizen Naturalization (or naturalisation) is the legal act or process by which a non-citizen of a country may acquire citizenship or nationality of that country. It may be done automatically by a statute, i.e., without any effort on the part of the in ...

of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. In 1963 Kohn became a Member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and ...

, a Member 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 ...

in 1969, and a member of the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

in 1994. In 2011, he became an honorary member of the Austrian Academy of Sciences (ÖAW). He was also a Member of the

International Academy of Quantum Molecular Science The International Academy of Quantum Molecular Science (IAQMS) 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 we ...

Death

Kohn died on April 19, 2016, at his home in

Santa Barbara, California Santa Barbara ( es, Santa Bárbara, meaning "Saint Barbara") is a coastal city in Santa Barbara County, California, of which it is also the county seat. Situated on a south-facing section of coastline, the longest such section on the West Co ...

from jaw cancer, at the age of 93.

Honors and awards

* Oliver E. Buckley prize in Solid State Physics ( American Physical Society, 1961) * Davisson-Germer Prize (American Physical Society, 1977) *

National Medal of Science The National Medal of Science is an honor bestowed by the President of the United States to individuals in science and engineering who have made important contributions to the advancement of knowledge in the fields of behavioral and social scienc ...

(1988) *

(1998) * Elected a Foreign Member of the Royal Society (ForMemRS) in 1998 *

Austrian Decoration for Science and Art The Austrian Decoration for Science and Art (german: Österreichisches Ehrenzeichen für Wissenschaft und Kunst) is a state decoration of the Republic of Austria and forms part of the Austrian national honours system. History The "Austrian ...

(1999) * Grand Decoration of Honour in Silver with Star for Services to the Republic of Austria (2008) *

awarded him an Honorary

Doctor of Science Doctor of Science ( la, links=no, Scientiae Doctor), usually abbreviated Sc.D., D.Sc., S.D., or D.S., is an academic research degree awarded in a number of countries throughout the world. In some countries, "Doctor of Science" is the degree used f ...

(May 2012)

Selected publications

* W. Kohn, "An essay on condensed matter physics in the twentieth century," R''eviews 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

References

External links

"Quantum Chemistry Comes of Age,"
''The Chemical Educator'', Vol. 5, No. 3, S1430-4171(99)06333-7, , © 2000 Springer-Verlag New York, Inc.
Freeview video interview with Walter Kohn by the Vega Science Trust
* including the Nobel Lecture, January 28, 1999 (a year later) ''Electronic Structure of Matter – Wave Functions and Density Functionals''
Kohn's faculty website
at University of California-Santa Barbara. Retrieved November 11, 2006.
Obituary
*