R-matrix calculation of low-energy electron collisions with uracil

R-matrix calculations on electron-uracil collisions are presented within the static exchange, static exchange plus polarization, and close-coupling approximations. Particularly as input for the close-coupling calculations, a series of target calculations is performed which considers low-lying singlet and triplet excited states of the uracil target. The scattering calculations find three low-lying shape resonances of 2A[double-prime] symmetry and three higher-energy Feshbach resonances of 2A[prime] symmetry. In both symmetries the precise resonance parameters are found to be sensitive to the treatment of polarization effects employed. Cross sections are presented for both elastic scattering and electronic excitation. Comparisons are made with energy-dependent, differential cross section measurements at 90° angle and good agreement is found for scattering energies above 0.5 eV