Koopmans' theorem in the statistical HartreeFock theory

Jean-Christophe Pain (1)

1 DAM/DIF - DAM Île-de-France

In this short paper, the validity of Koopmans ' theorem in the Hartree-Fock theory at non-zero temperature (Hartree-Fock statistical theory) is investigated. It is shown that Koopmans ' theorem does not apply in the grand-canonical ensemble, due to a missing contribution to the energy proportional to the interaction between two electrons belonging to the same orbital. Hartree-Fock statistical theory has also been applied in the canonical ensemble [ Blenski et al., Phys. Rev. E 55, R4889 (1997) ] for the purpose of photo-absorption calculations. In that case, the Hartree-Fock selfconsistent-field equations are derived in the super-configuration approximation. It is shown that Koopmans ' theorem does not hold in the canonical ensemble, but that a restricted version of the theorem can be obtained, by assuming that a particular quantity multiplying the interaction matrix element in the expression of the energy does not change during the removal of an electron.

Mots clés: 31.15.bt; 31.15.xr; 31.15.-p

Jean-Christophe Pain. Koopmans' theorem in the statistical HartreeFock theory. Journal of Physics B: Atomic, Molecular and Optical Physics, 2011, 44 (14), pp.145001. ⟨10.1088/0953-4075/44/14/145001⟩. ⟨hal-00636638⟩