THE 2-PARTICLE ONE HOLE-TAMM-DANCOFF APPROXIMATION (2PH-TDA) DECOUPLING OF THE DILATED ELECTRON PROPAGATOR WITH APPLICATION TO P-2 SHAPE RESONANCES IN E-BE, E-MG, AND E-CA SCATTERING

Abstract

Formulas for the renormalized full two-particle one hole-Tamm-Dancoff approximation (2ph-TDA) decoupling of the dilated biorthogonal electron propagator based on complex scaled bivariational self-consistent-field (SCF) procedure are derived and the diagonal 2ph-TDA approximation is implemented for the first time. The 2P shape resonances in e-Be, e-Mg, and e-Ca scattering are characterized using the diagonal 2ph-TDA, the second-order and the zeroth-order (bivariational SCF) approximations to the dilated electron propagator. A comparative investigation of these different decouplings reveals that although the resonance energies and widths depend on the level of correlation employed, greater correlation need not lead to sharper resonances.