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Named after Dutch-American mathematician Tjalling Koopmans (1910–1985), who published this result in 1934.
Etymology from Wiktionary, CC BY-SA 4.0.
Koopmans' theorem
Today it means: A theory stating that, in closed-shell Hartree-Fock theory, the first ionization energy of a molecular system is equal to the negative of the orbital energy of the highest occupied molecular orbital (HOMO). Full definition →