On August 29, 2018, the eminent physicist Clemens C.J. Roothaan, who is a member of the Society of Catholic Scientists, will celebrate his 100th birthday. As a physicist, he is most famous for developing a method for calculating atomic and molecular wave functions that leads to the so-called Hartree-Fock-Roothaan equations.  He also played an important part in the development of supercomputers. 

Clemens C.J. Roothaans was born in Nijmegen, Holland. His studies in electrical engineering at Delft University of Technology were interrupted by the outbreak of World War II.  He and his brother were sent by the Nazis to the Vught concentration camp for involvement with the Dutch Resistance.  Later they were transferred to the Sachsenhausen concentration camp in Germany.  Near the end of the war, the inmates of that camp, including the Roothaan brothers, were sent on a “death march”, which his brother did not survive. 

After the war, Clemens emigrated to the United States and studied with Prof. Robert S. Mulliken, receiving his PhD from the University of Chicago in 1950. He remained at the University of Chicago, where for many years he held he position of Louis Block Professor of Chemistry and Physics, retiring in 1988.  From 1962-1968 he was also Director of the University of Chicago Computation Center. After his retirement from University of Chicago in 1988, he worked for two decades for Hewlett-Packard Laboratories in Palo Alto, California, contributing to the development of the mathematical coprocessor routines for the Itanium chip.

Prof. Roothaan is a man of deep Catholic faith.  He returned to the practice of his faith after 67 years on November 23^th, 2014.  November 23^th is a special day for Prof. Roothaan for two other reasons as well.  It is the feast day of his patron St. Clement of Rome, and the birthday of his great-great-great uncle, Jan Philipp Roothaan, who was the Superior General of the Jesuit order from 1829 to 1853.  A year after Prof. Roothaan’s return to the Church, his beloved wife of more than six decades, Judith, who was Jewish but not a believer, came to faith and was received into the Catholic Church.  Prof. Roothaan is a parishioner at the Shrine of Christ the King, Sovereign Priest, which worships in the Extraordinary Form of the Roman Rite.

On August 27^th, the president of the Society of Catholic Scientists visited Prof. Roothaan at his home near the University of Chicago and presented him with a letter from the Society congratulating him on his 100^th birthday and informing him that his intentions will be prayed for by members of the Society on his birthday and at all the Gold Masses that will be celebrated this coming November.  Prof. Roothaan expressed his gratitude for this and for the work of the Society of Catholic Scientists.  He also expressed his puzzlement that some see belief in God and science as opposed. Please remember Clemens Roothaan’s intentions in your prayers, especially on August 29th.