Polarization effects on electronic excitation of molecules by low-energy electron impact: Study on $e^-$-furan scattering
Romarly F. da Costa, M\ ' { a} rcio H. F. Bettega, and Marco A. P. Lima

The Schwinger multichannel method is applied to study the influence of polarization effects on the electronic excitation of the furan molecule by low-energy electron impact. We discuss the importance of inclusion of these effects through the comparison of theoretical results for the electronic excitation of the $^3B_2$ state of furan obtained with and without the proper treatment of the polarization of the target. The electron-furan scattering presents two prominent shape resonances in the $^2A_2$ and $^2B_1$ symmetries at around the electronic excitation threshold of the $^3B_2$ state (3.7~eV). At this low-energy, the inclusion of polarization effects in the calculation moves to lower energies the resonances positions obtained either in the close-coupling or in the static-exchange level of approximation. This phenomenon strongly influences the electronic excitation process. The present results show that a simple close-coupling calculation can not be applied for molecular systems with low-energy electronic excitation thresholds around misplaced resonances.

© 2008 The American Physical Society.