Shape resonances in the elastic scattering of slow electrons by pyridine

We present cross sections for elastic scattering of low-energy electrons with the N-heterocyclic molecule pyridine. We employed the Schwinger multichannel method implemented with pseudopotentials in the static-exchange and static-exchange-polarization approximations, for energies ranging from 0.1 to 12 eV. The calculated integral cross section presents two low-lying shape resonances of pi* nature belonging to the B-1 and A(2) symmetries and a higher lying resonance, belonging to the B-1 symmetry, which is a mixture of shape and core-excited resonances. The computed resonance positions are in reasonable agreement with the vertical attachment energy data of Nenner and Schulz [J. Chem. Phys. 62, 1747 (1975)] and Modelli and Burrow [J. Electron Spectrosc. Relat. Phenom. 32, 263 (1983)]. We compare the present calculated differential cross sections with the experimental data for benzene, pyrimidine, and pyridazine.