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

Formulas for the renormalized full two-particle one hole-Tamm-Dancoff approximation (2ph-TDA) decoupling of the dilated biorthogonal electro n propagator based on complex scaled bivariational self-consistent-fie ld (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) approximatio ns to the dilated electron propagator. A comparative investigation of these different decouplings reveals that although the resonance energi es and widths depend on the level of correlation employed, greater cor relation need not lead to sharper resonances.