Toward the understanding of He2− excited states

Using a recently developed state-specific method for the calculation of wavefunctions of diatomic molecules (N.C. Bacalis, Y. Komninos and C.A. Nicolaides, Phys. Rev. A 45 (1992) 2701), we calculated the potential energy curve for a localized wavefunction of a 4Φg(1σg21σu2πu1δg) state in He2−, including including electron correlation. This state is a Feshbach resonance, lying below its parent He2 3Πg(1σg21σu2πu) and 3Δu(1σg2 1σu1δg) excited states and autoionizing into the continuum of He2 3Πg(1σg21σu1πu) by the two-orbital rearrangement 2πu1δg → 1πuϵδg or 1πuϵγg (in σ, π, δ, ϕ, γ 3. diatomic notation). From our state-specific numerical Hartree-Fock calculations it can be concluded that the localized solution for the 4Ig(1σg21σu1δg1ϕu) state obtained by L. Adamowicz and T.P. Pluta (Chem. Phys. Letters 179 (1991) 517), should five rise to a shape resonance above the lowest He2 3Δu(1σg21σu1δg) state.