Life and Science of Clemens C. J. Roothaan

Clemens Roothaan, a Nazi concentration camp survivor and Professor Emeritus of the University of Chicago, passed away on 17 June 2019, 10 months after celebrating his 100th anniversary. For his doctoral thesis, Roothaan developed the matrix version of the Hartree-Fock equations. These Hartree-Fock-Roothaan equations form the cornerstone of atomic and molecular structure theory. In addition, Roothaan devised computing methods for quantum chemistry, physics, and other scientific fields from the early years. After 1988, he actively helped Hewlett Packard develop the Intel Itanium processor. This article presents the highlights of the life and science of Roothaan.