Hans Gustav Adolf Hellmann (October 14, 1903 – May 29, 1938) was a German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 theoretical physicist

Physicist

A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

.

Hellmann was born in Wilhelmshaven

Wilhelmshaven

Wilhelmshaven is a coastal town in Lower Saxony, Germany. It is situated on the western side of the Jade Bight, a bay of the North Sea.-History:...

, Prussian Hanover. He began studying electrical engineering in Stuttgart

University of Stuttgart

The University of Stuttgart is a university located in Stuttgart, Germany. It was founded in 1829 and is organized in 10 faculties....

, but changed to engineering physics

Engineering physics

Engineering physics is the study of the combined disciplines of physics, engineering and mathematics in order to develop an understanding of the interrelationships of these three disciplines. Fundamental physics is combined with problem solving and engineering skills, which then has broad...

 after a semester. Hellmann also studied at the University of Kiel

University of Kiel

The University of Kiel is a university in the city of Kiel, Germany. It was founded in 1665 as the Academia Holsatorum Chiloniensis by Christian Albert, Duke of Holstein-Gottorp and has approximately 23,000 students today...

.

He received his diploma from the Kaiser Wilhelm Institute for Chemistry in Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 under Otto Hahn

Otto Hahn

Otto Hahn FRS was a German chemist and Nobel laureate, a pioneer in the fields of radioactivity and radiochemistry. He is regarded as "the father of nuclear chemistry". Hahn was a courageous opposer of Jewish persecution by the Nazis and after World War II he became a passionate campaigner...

 and Lise Meitner

Lise Meitner

Lise Meitner FRS was an Austrian-born, later Swedish, physicist who worked on radioactivity and nuclear physics. Meitner was part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn was awarded the Nobel Prize...

. He received his Ph.D. at Stuttgart with Prof. Erich Regener

Erich Regener

Erich Rudolf Alexander Regener was a German physicist known primarily for the design and construction of instruments to measure cosmic ray intensity at various altitudes....

, who was also the landlord of his future spouse Victoria Bernstein. In 1929 Hellmann became assistant professor at the University of Hanover.

After the Nazi

Nazism

Nazism, the common short form name of National Socialism was the ideology and practice of the Nazi Party and of Nazi Germany...

 rise to power

Machtergreifung

Machtergreifung is a German word meaning "seizure of power". It is normally used specifically to refer to the Nazi takeover of power in the democratic Weimar Republic on 30 January 1933, the day Hitler was sworn in as Chancellor of Germany, turning it into the Nazi German dictatorship.-Term:The...

, Hellmann was dismissed on December 24, 1933 as ‘undesirable’ because of his Jewish wife. He immigrated to the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

, taking up a position in Moscow

Moscow

Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

. However, he was later denounced during the Great Purge

Great Purge

The Great Purge was a series of campaigns of political repression and persecution in the Soviet Union orchestrated by Joseph Stalin from 1936 to 1938...

, imprisoned on 10 May 1938, and executed on 29 May. His son, Hans Hellmann, Jr., was only allowed to leave the former Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 in 1991.

In science, his name is primarily associated with the Hellmann–Feynman theorem, as well as with one of the first-ever textbooks on quantum chemistry

Quantum chemistry

Quantum chemistry is a branch of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems...

 (‘Kvantovaya Khimiya’, 1937; translated into German as ‘Einfuehrung in die Quantenchemie’, Vienna

Vienna

Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...

, 1937). He pioneered several approaches now commonplace in quantum chemistry, notably the use of pseudopotential

Pseudopotential

In physics, a pseudopotential or effective potential is used as an approximation for the simplified description of complex systems. Applications include atomic physics and neutron scattering.- Atomic physics :...

s.