THE (2)PI(G) SHAPE RESONANCE IN ELECTRON-ACETYLENE SCATTERING - AN INVESTIGATION USING THE DILATED ELECTRON PROPAGATOR METHOD

The zeroth order (Sigma(0)), the second order (Sigma(2)), the diagonal two particle-one hole Tamm Dancoff approximation (Sigma(2ph-TDA)) and the corresponding quasi-particle decouplings of the dilated electron propagator have been used to investigate the (2)Pi(g) C2H2- shape reso nance. The results compare favourably with the experimental and other theoretical results. A plot of the resonant Feynman-Dyson Amplitudes e stablishes that the capture of the impinging electron is indeed in the pi(g) orbital of the acetylene molecule. The resonant orbital on the real line shows the attributes of the acetylene lowest unoccupied mol ecular orbital and for the optimal complex scaling parameter shows a d epletion of electron density near the carbon nuclei. (C) 1998 Elsevier Science B.V. All rights reserved.