Clemens C. J. Roothaan, Date of Birth, Place of Birth, Date of Death

    

Clemens C. J. Roothaan

Dutch-American physicist

Date of Birth: 29-Aug-1918

Place of Birth: Nijmegen, Gelderland, Netherlands

Date of Death: 17-Jun-2019

Profession: physicist, chemist, university teacher

Nationality: Kingdom of the Netherlands

Zodiac Sign: Virgo


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About Clemens C. J. Roothaan

  • Clemens C.
  • J.
  • Roothaan (August 29, 1918 – June 17, 2019) was a Dutch physicist and chemist known for his development of the self-consistent field theory of molecular structure. Roothaan was born in Nijmegen.
  • He enrolled TU Delft in 1935 to study electrical engineering.
  • During World War II he was first detained in a prisoner of war camp.
  • Later he and his brother were sent to the Vught concentration camp for involvement with the Dutch Resistance.
  • On September 5, 1944, the remaining prisoners of the camp (including the Roothaan brothers) were moved to the Sachsenhausen camp in Germany ahead of the advancing Allies.
  • Near the end of the war, the Sachsenhausen inmates were sent on a death march which Roothaan's brother did not survive.While a prisoner of war he was able to pursue his studies in physics together with other professors and students under the formal guidance of Philips.
  • The work he was assigned to while cooperating with Philips was a foundation for his master's thesis.
  • He obtained his master's degree in physics from TU Delft on October 14, 1945.
  • After that he moved to USA, where he did his PhD thesis with Robert S.
  • Mulliken from the University of Chicago, on semiempirical MO theory, while holding a post at The Catholic University of America in Washington, D.C..
  • He realised that the then current approach to molecular orbital theory was incorrect and changed his topic to what resulted in the development of the Roothaan equations.
  • Prof.
  • Mulliken mentions this work in his Nobel lecture as follows: He had moved to the University of Chicago in 1949 and his PhD was awarded in 1950.
  • He then joined the Physics Department of the University of Chicago.
  • From 1962 to 1968 he was Director of the University of Chicago Computation Center.
  • Later he was Professor of Physics and Chemistry at the University of Chicago.
  • Since his retirement, in 1988, he has worked for the Hewlett-Packard Laboratories in Palo Alto, California, where his primary contribution has been in the development of the mathematical coprocessor routines for the Itanium chip.
  • His method of analyzing pipeline architecture has been unique and innovative and greatly admired in supercomputer circles around the world. In 1982 Roothaan became a correspondent of the Royal Netherlands Academy of Arts and Sciences.
  • He was a member of the International Academy of Quantum Molecular Science and the Society of Catholic Scientists.
  • He turned 100 in August 2018 and died in June 2019.

Read more at Wikipedia

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