Clemens C. J. Roothaan
Clemens CJ Roothaan ( born August 29, 1918 in Nijmegen) is a Dutch physicists, chemists and computer architect.
Life and work
He matriculated in 1935 at the Delft University of Technology for a degree in electrical engineering, and studied intermittently at the University of Karlsruhe. He hears among other lectures by Hendrik Anthony Kramers and Kronig Ralph. During the Second World War and the occupation of the Netherlands, he and his brother first imprisoned for resisting the occupation of aiding and abetting, and later they were taken to a concentration camp in Vught Netherlands. While in detention, he was able to continue his studies in physics together with other interned professors and students under the formal leadership of Philips. The camp inmates were transferred on September 5, 1944 because of the approaching Allied organizations in the Sachsenhausen concentration camp in Oranienburg, where Roothaan was part of a 'construction. On April 20th of the following year, he was forced together with the surviving inmates to death march towards the Baltic Sea, which but 12 days later dissolved in Schwerin. His brother did not survive the concentration camps.
The Philips Centre delivered the final report sent his education at the makeshift "university" in the concentration camps was recognized him on 14 October 1945 by the TU Delft for the acquisition of the engineer 's degree. In January 1946, Roothaan changed with the help of a scholarship in the USA at the University of Chicago. At that time, Chicago was one of the focal points of the physics professors as Enrico Fermi, Edward Teller, Maria Goeppert- Mayer, Robert Mulliken, James Franck and Leo Szilard. Since he was excluded as a foreigner by the programs for nuclear physics, he turned to quantum chemistry, and began a doctoral thesis with Robert S. Mulliken. His research topic was based on semi-empirical calculations to benzenes molecular orbital theory. He recognized that the approach used at this time was formally wrong and changed his approach, which subsequently led to the development of the Roothaan equations in quantum chemistry have been radically (see chemical bonding ) and a Hartree- Fock method with non-orthogonal basis functions are. They are sometimes also called by George G. Hall, who independently found 1951 Roothaan - Hall equations. Roothaans publication was one of the most cited papers. Mulliken mentioned Roothaans work in his Nobel Lecture (1966 ) as follows:
I tried to get Roothaan, his doctoral thesis on calculations of substituted benzenes to base using the Hückel method. But after some very good calculations he began to revolt against the Hückel method, threw his excellent calculations out the window, eventually developed his thesis completely independent his now well-known all- electron LCAO SCF self-consistent - field method for the calculation of atomic and molecular wave functions, now appropriately called, I believe, the Hartree -Fock - Roothaan method.
I tried to induce Roothaan to do his Ph.D.thesis on Hückel -type calculations on Substituted benzenes. But after carrying out some very good calculations on thesis he revolted against the Hückel method, threw his excellent calculations out the window, and for his thesis developed Entirely Independently his now well known all- electron LCAO SCF self-consistent -field method for the calculation of atomic and molecular wavefunctions, now Appropriately referred by to, I believe, as the Hartree -Fock - Roothaan method.
During his doctoral work Roothaan was with Karl Ferdinand Herzfeld at the Catholic University of America in Washington, DC employed (on mediation by Maria Goeppert- Mayer). In 1949 he got a job at the University of Chicago, and his doctorate in 1950. Thereafter he devoted a considerable portion of his time to the numerical calculation of molecular orbitals, based on its LCAO SCF method (SCF for Self Consistent Field). It was 1950 Instructor of Physics and Chemistry in Chicago, was from 1965 to 1968 professor of communications and computer science from 1962 to 1968 he was director of the Computer Center of the University of Chicago ( University of Chicago Computation Centre), and then professor of physics and chemistry at the University of Chicago (Louis block Professor ). He took his staff in the 1960s and 1970s, extensive computer calculations for quantum chemistry. In the 1970s, he was with his student John Detrich leader in the development of efficient multi- configuration calculations of self-consistent field ( MCSCF ). Already in the 1960s he was a consultant at IBM supercomputer development.
After his retirement in 1988, he worked for Hewlett -Packard Laboratories in Palo Alto, California, where his most important contributions in the development of math coprocessor routines for the Itanium chip series were. His method for the analysis of pipeline architectures was unique and innovative and is highly valued in supercomputing experts.
He is a member of the International Academy of Quantum Molecular Science, member (Member) of the American Physical Society, corresponding member of the Netherlands Academy of Sciences and an honorary member of Gelato Foundation. In 1957 he was on a Guggenheim Fellow at the University of Cambridge. 1958 to 1966 he was an advisor to the Argonne National Laboratory, 1960-1965 Consultant to Lockheed, from 1965 by Union Carbide and IBM. He was a visiting professor at Ohio State University (1976) and at the Technical University Lyngby (1983).