Electron propagator calculations on the adiabatic electron binding energies of C3

Abstract

New techniques of electron propagator theory (EPT) are applied to C3, C3+, and C3−. Gradients of second-order EPT ionization energies and electron affinities are combined with gradients of second-order many-body perturbation theory for the neutral to produce gradients of the ion total energies. Optimized geometries of the ions, vibrational frequencies, and adiabatic electron binding energies are calculated with these methods. A renormalized self-energy is used to produce improved vertical and adiabatic ionization energies and electron affinities. For the cation, the 2B2 state with C2v symmetry and the 2Σ state with C∞v symmetry are very close in energy. The optimized 2Σu structure is a transition state with an imaginary frequency of σu symmetry that lies 2.8 kcal/mol above the 2B2 state. The adiabatic ionization energy is calculated to be 11.9 eV. The anion in the 2Πg state lies 1.8 eV below the neutral in these calculations.