Koopmans' theorem

English Etymology en Tjalling Koopmans 1910 1985 Dutch-American mathematician, who published this result in 1934. Proper noun Koopmans' theorem en chemistry 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). en 2016-04-26 Jie Ma; Lin-Wang Wang Using Wannier functions to improve solid band gap predictions in density functional theory w:Scientific Reports 6 article 24924 1 10.1038/srep24924 There exists another approach to correct the DFT and its related Kohn-Sham Hamiltonian: the Koopmans’ theorem11–22. The original Koopmans’ theorem only states that in Hartree-Fock, the first ionization energy is equal to the highest occupied orbital energy if the wave function relaxations are ignored. In the literature11–21, the terminology “Koopmans’ theorem” was used to indicate the straight-line condition (SLC) of the total energy E(n) as a function of the continuous number of electrons n between two integer points23.