Capel was born on 3 June 1936 in Sceaux, France. He obtained his PhD in mathematics and physics at
Leiden University in 1965 under with a dissertation titled:
The hole-equivalence principle, the Van Vleck relation and the application to the theory of d-ions in Ligand fields. Capel subsequently became a lector of theoretical physics at the same university in 1970, and served as professor in the same field between 1979 and 1983. He also served as editor of
Physica A. Capel died in
Haarlem on 7 April 2023 after a short illness. ==References==