The parameter dependence of calculated koopmans'defects in the framework of a model hamiltonian verified in the case of transition metal compounds

The validity of Koopmans' theorem in the lower energy region of trimethylenemethane iron tricarbonyl (1) is studied by means of a semi-empirical IN Reorganization energies are investigated as a function of the one-electron resonance integral β_μυ^AB and as a function of the one- and two interaction (γ_μυ^AA, K_μυ^AA and γ_μυ^AB). β_μυ^AB determines the kinetic energy of the interacting enlarged kinetic energy. The two-center electron repulsion intergral γ_μυ^AB have been calculated by means of an exponential formula with a short-range potentials with large γ_μυ^AB gradients pronounced reorganization energies are predicted while negligible defects even for stro case of smooth repulsion potentials with small γ_μυ^AB gradients. The largest parameter dependence of the calculated reorganization energie one-center electron—electron interaction integrals. With enlarged γ_μυ^AA and K_μυ^AA values enhanced Koopmans' defects are calculted in the framework of many body perturbation theory based on the Green's function formalism. A renormalized diagonal approximation for the self and correlation increments. The net defects are predominantly determined by electronic relaxation and modifications of the correlation energy in the ca of ground state pair-correlation (pair-removal) is only of minor importance.