# Walter Kohn

> American physicist (1923–2016)

**Wikidata**: [Q78510](https://www.wikidata.org/wiki/Q78510)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Walter_Kohn)  
**Source**: https://4ort.xyz/entity/walter-kohn

## Summary
Walter Kohn was an American physicist and chemist best known for developing density functional theory (DFT), a groundbreaking computational method in quantum mechanics that revolutionized the study of electronic structures in atoms and molecules. His work earned him the Nobel Prize in Chemistry in 1998 and established him as a foundational figure in theoretical physics and computational chemistry.

## Biography
- **Born**: 1923 (Austria)
- **Died**: 2016
- **Nationality**: American (naturalized)
- **Education**: Akademisches Gymnasium (high school), University of Toronto, Harvard University
- **Known for**: Pioneering density functional theory (DFT) and the Kohn–Sham equations
- **Employer(s)**:
  - University of California, Santa Barbara
  - University of California, San Diego
  - Carnegie Mellon University
  - Harvard University (as a student and later honorary doctorate recipient)
- **Field(s)**: Theoretical physics, quantum chemistry, condensed matter physics

## Contributions
Walter Kohn's most significant contribution was the development of **density functional theory (DFT)**, a computational framework that allows scientists to model the electronic structure of atoms, molecules, and solids with high efficiency. Introduced in the 1960s, DFT replaced more complex wavefunction-based methods, making quantum mechanical calculations feasible for larger systems. His **Kohn–Sham equations** (1965) provided a practical way to apply DFT by transforming the many-body problem into a set of one-electron Schrödinger equations, enabling widespread adoption in chemistry, materials science, and physics.

Kohn also made foundational contributions to **condensed matter physics**, particularly in the study of surface physics and semiconductor properties. His work on the **electron density distribution** in solids laid the groundwork for modern computational materials design.

## FAQs

**What is Walter Kohn best known for?**
Walter Kohn is best known for developing **density functional theory (DFT)**, a computational method that simplifies quantum mechanical calculations by focusing on electron density rather than wavefunctions. This innovation earned him the **Nobel Prize in Chemistry in 1998** and became a cornerstone of modern computational chemistry and materials science.

**Where did Walter Kohn study and work?**
Kohn attended the **Akademisches Gymnasium** in Vienna before fleeing Nazi-occupied Austria. He earned his undergraduate degree at the **University of Toronto** and his Ph.D. at **Harvard University**. He held academic positions at **Carnegie Mellon University**, the **University of California, San Diego**, and the **University of California, Santa Barbara**, where he spent much of his career.

**What awards did Walter Kohn receive?**
Kohn received numerous prestigious awards, including:
- **Nobel Prize in Chemistry (1998)**
- **National Medal of Science (1988)**
- **Oliver E. Buckley Condensed Matter Prize (1961)**
- **Davisson–Germer Prize in Atomic or Surface Physics (1977)**
- **Austrian Decoration for Science and Art**
- **UNESCO Niels Bohr Medal**
- Multiple honorary doctorates from institutions such as **Harvard University**, the **University of Vienna**, and the **Weizmann Institute of Science**.

**What is the Kohn–Sham equation?**
The **Kohn–Sham equations** are a set of one-electron Schrödinger equations used in density functional theory to approximate the behavior of electrons in a system. By introducing a fictitious system of non-interacting electrons, these equations make DFT computationally practical while retaining accuracy, enabling simulations of complex molecular and material systems.

**Which scientific societies was Walter Kohn affiliated with?**
Kohn was a member of several esteemed scientific organizations, including:
- **National Academy of Sciences (U.S.)**
- **Royal Society (U.K.)**
- **Austrian Academy of Sciences**
- **American Academy of Arts and Sciences**
- **Russian Academy of Sciences**
- **International Academy of Quantum Molecular Science**
- **American Philosophical Society**
- **Bavarian Academy of Sciences and Humanities**

## Why They Matter
Walter Kohn’s development of **density functional theory (DFT)** transformed computational chemistry and materials science by providing a practical, efficient method to model electronic structures. Before DFT, quantum mechanical calculations were computationally prohibitive for all but the simplest systems. Kohn’s work enabled researchers to simulate complex molecules, solids, and surfaces, accelerating discoveries in catalysis, semiconductor design, and drug development.

His **Kohn–Sham equations** bridged the gap between theoretical physics and applied chemistry, making DFT the most widely used method in computational materials research today. Without his contributions, fields like nanotechnology, renewable energy materials, and computational drug design would lack the foundational tools they rely on.

Kohn’s influence extends beyond his theoretical work. As a mentor and educator at institutions like **UC Santa Barbara** and **UC San Diego**, he shaped generations of physicists and chemists. His interdisciplinary approach—spanning physics, chemistry, and materials science—set a precedent for collaborative research in computational sciences.

## Notable For
- **Nobel Prize in Chemistry (1998)** for developing density functional theory.
- **Pioneer of the Kohn–Sham equations**, enabling practical DFT calculations.
- **National Medal of Science (1988)** for contributions to condensed matter physics.
- **Oliver E. Buckley Condensed Matter Prize (1961)** for early work in solid-state physics.
- **Member of multiple national academies**, including the U.S. National Academy of Sciences, the Royal Society, and the Austrian Academy of Sciences.
- **Honorary doctorates** from Harvard, the University of Vienna, the Weizmann Institute, and others.
- **Foundational role in computational quantum chemistry**, making large-scale electronic structure calculations feasible.
- **Eponymous recognition**: The **Kohn–Sham equations** are a standard tool in computational physics and chemistry.

## Body

### Early Life and Education
Walter Kohn was born in **1923 in Vienna, Austria**, into a Jewish family. His early education took place at the **Akademisches Gymnasium**, one of Austria’s oldest and most prestigious high schools. Following the **Anschluss in 1938**, Kohn fled Nazi persecution, emigrating first to England and later to **Canada**, where he enrolled at the **University of Toronto**. He earned his **Bachelor of Applied Science in 1945** and a **Master’s in Applied Mathematics in 1946**.

Kohn then moved to the **United States** to pursue his Ph.D. at **Harvard University**, studying under **Julian Schwinger**, a future Nobel laureate in physics. He completed his doctorate in **1948**, focusing on theoretical physics.

### Academic Career and Research
Kohn’s academic career began at **Carnegie Mellon University** (then Carnegie Institute of Technology), where he worked from **1950 to 1960**. During this period, he made early contributions to **solid-state physics**, particularly in understanding the electronic properties of metals and semiconductors.

In **1960**, Kohn joined the **University of California, San Diego (UCSD)**, where he continued his work on **many-body theory** and **surface physics**. His research on **electron density** in solids laid the groundwork for his later breakthroughs.

By **1979**, Kohn moved to the **University of California, Santa Barbara (UCSB)**, where he became the founding director of the **Institute for Theoretical Physics** (now the **Kavli Institute for Theoretical Physics**). At UCSB, he further developed **density functional theory**, collaborating with **Lu Jeu Sham** to formulate the **Kohn–Sham equations** in **1965**. This work provided a practical framework for applying DFT to real-world systems, revolutionizing computational chemistry.

### Density Functional Theory and the Kohn–Sham Equations
Kohn’s most enduring contribution is **density functional theory (DFT)**, which he introduced in **1964–1965**. Unlike traditional quantum mechanical methods that rely on complex wavefunctions, DFT focuses on **electron density**, a simpler three-dimensional function. This shift drastically reduced computational complexity while maintaining accuracy.

The **Kohn–Sham equations**, published in **1965**, were a critical advancement. They recast the many-body problem of interacting electrons into a set of **one-electron Schrödinger equations** for a fictitious non-interacting system. This innovation made DFT accessible for practical applications, from **materials science** to **biochemistry**.

DFT’s impact is vast:
- **Materials Science**: Enabled the design of new semiconductors, superconductors, and nanomaterials.
- **Chemistry**: Accelerated drug discovery and catalytic research by allowing precise molecular modeling.
- **Physics**: Provided insights into the electronic structure of solids, surfaces, and interfaces.

### Awards and Honors
Kohn’s contributions were recognized with numerous awards, including:
- **Nobel Prize in Chemistry (1998)** – Shared with **John Pople** for DFT.
- **National Medal of Science (1988)** – Awarded by the U.S. government for his work in condensed matter physics.
- **Oliver E. Buckley Condensed Matter Prize (1961)** – For his early contributions to solid-state theory.
- **Davisson–Germer Prize (1977)** – For advancements in surface physics.
- **Austrian Decoration for Science and Art** – Recognizing his Austrian roots and global impact.
- **UNESCO Niels Bohr Medal** – For outstanding contributions to physics.

He also received **honorary doctorates** from:
- **Harvard University**
- **University of Vienna**
- **Dresden University of Technology**
- **Weizmann Institute of Science**
- **University of Paris-XI**

### Memberships in Scientific Societies
Kohn was elected to multiple prestigious academies, reflecting his interdisciplinary influence:
- **U.S. National Academy of Sciences**
- **Royal Society (UK)**
- **Austrian Academy of Sciences**
- **American Academy of Arts and Sciences**
- **Russian Academy of Sciences**
- **American Philosophical Society**
- **Bavarian Academy of Sciences and Humanities**
- **International Academy of Quantum Molecular Science**

### Later Life and Legacy
After retiring from active research, Kohn remained engaged in scientific discourse, advocating for **open access to research** and **international collaboration**. He passed away in **2016**, leaving behind a legacy that continues to shape computational science.

Today, **density functional theory** is the **most widely used method** in computational chemistry and materials science, with applications ranging from **battery design** to **protein folding simulations**. The **Kohn–Sham equations** remain a standard tool in quantum mechanical modeling, ensuring his enduring influence on both theoretical and applied research.

Kohn’s work exemplifies the power of **interdisciplinary science**, bridging physics, chemistry, and materials engineering. His contributions have not only advanced fundamental understanding but also enabled technological innovations that define modern science.

## References

1. [Source](http://www.noozhawk.com/article/physicist_walter_kohn_ucsb_nobel_laureate_dies_at_93)
2. Integrated Authority File
3. [Source](http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1998/)
4. [Source](https://www.nobelprize.org/nobel_prizes/about/amounts/)
5. [Source](https://www.aps.org/programs/honors/prizes/buckley.cfm)
6. [Source](http://geschichte.univie.ac.at/en/persons/walter-kohn-prof-dr)
7. [Source](https://tu-dresden.de/mn/der-bereich/ehrendoktoren-1?set_language=en)
8. [Source](https://www.weizmann.ac.il/acadaff/awards-and-honors/institute-honors-and-prizes/phd-honoris-causa)
9. [Source](https://www.aps.org/programs/honors/prizes/davisson-germer.cfm)
10. Complete List of Royal Society Fellows 1660-2007
11. [Source](https://www.harvard.edu/on-campus/commencement/honorary-degrees)
12. [Journal officiel de la République française. 1980](https://www.legifrance.gouv.fr/jorf/jo/id/JORFCONT000000023255)
13. Mathematics Genealogy Project
14. Virtual International Authority File
15. NNDB
16. Encyclopædia Britannica Online
17. SNAC
18. Solomon R. Guggenheim Museum
19. Brockhaus Enzyklopädie
20. BnF authorities
21. Munzinger Personen
22. Great Norwegian Encyclopedia
23. Freebase Data Dumps. 2013
24. Norwegian Authority File: Persons and Corporate Bodies
25. CONOR.SI
26. [Source](https://mix-n-match.toolforge.org/#/entry/63770732)