Theoretica Chimica Acta

, Volume 40, Issue 2, pp 129–141 | Cite as

Konsequenzen des Koopmansschen Theorems in den Restricted Hartree Fock Methoden für open-shell-Systeme

  • Joachim Sauer
  • Christoph Jung

Consequences of Koopmans' theorem in the restricted Hartree Fock methods for open shell systems


The application of Koopmans' theorem to open shell systems shows — compared with closed shell systems — an important difference: a mixture of one-electron-states of theN-electron system is needed for the quantum mechanical description of the (N – 1)-electron system. The ionization potentials are obtained as eigenvalues of a special matrix. Equations for the elements of thisI-matrix were derived which are applicable to systems having a doublet ground state. The derivation was carried out for the procedures developed by Roothaan, Kruglyak, McWeeny, Longuet-Higgins, and Pople and Nesbet using the density matrix formalism. First numerical calculations suggest that the effects which are taken into account in the exact form of Koopmans' theorem are important.

Key words

Koopmans' theorem application of ∼ to open shell systems Open shell systems, Koopmans' theorem in RHF methods for ∼ 


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Copyright information

© Springer-Verlag 1975

Authors and Affiliations

  • Joachim Sauer
    • 1
  • Christoph Jung
    • 1
  1. 1.Sektion Chemie der Humboldt-Universität zu BerlinBerlinDDR

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