On the 2IIg shape resonance in electron-C2H2 scattering

The 2Πg shape resonance of the electron-C2H2 system in the vicinity of 2 eV is investigated under several local models for exchange interaction depending upon free-electron-gas and semiclassical theories. It is found that the modified version of the semiclassical exchange model, recently proposed by Gianturco and Scialla is a very successful model in reproducing the 2Πg shape resonance features in agreement with experimental studies on the electron-C2H2 collision. The polarization force is included parameter-free in the correlation-polarization approximation. The scattering problem is solved in the fixed-nuclei approximation under the close-coupling formalism. (Author)