Effective configurations in electron-molecule scattering. II

We present results of the application of the Schwinger multichannel method using effective configurations [Azevedo et al., Phys. Rev. A 61, 042702 (2000)] to study special features of low-energy electron-molecule scattering, such as (i) the shape resonance in e^--N₂ scattering; (ii) the Ramsauer-Townsend minimum in e^--CH₄ scattering; and (iii) a Feshbach resonance in e^--H₂ scattering (in a two-channel coupling calculation including polarization effects). In all cases, we find that the use of effective configurations to describe polarization effects allows a substantial reduction of the configuration space, without any loss of quality of the results. The present applications (together with our previous study of nonresonant electron-H₂ scattering) indicate that this technique will be very useful in the analysis of more complex systems.