text: Hermann Hartmann (4 May 1914 in Bischofsheim an der Rhön – 22 October 1984 in Glashütten im Taunus) was a German chemist and professor and researcher in  physical and theoretical chemistry at the University of Frankfurt am Main. He contributed to all fields of physical chemistry and was instrumental in establishing  theoretical chemistry by developing Ligand field theory (1947) and other quantum chemical models including the Hartmann Potential (1971).  He also formulated a new perturbation theory (1970–1977) as part of his  pioneering research towards a unified field theory of chemical bonding based on a non-linear Schrödinger equation (1980).