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 (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).