Cross-section calculations for positron scattering from pyrimidine over an energy range from 0.1 to 10000 eV

We report a computational investigation of positron scattering by pyrimidine (C₄H₄N₂) in the gas phase. Integral and differential cross sections have been calculated over a broad energy range by employing two distinct ab initio quantum scattering methods: the R-matrix method and a corrected form of the independent-atom representation, at low and high energies, respectively. Since pyrimidine is a strong polar molecule further dipole-induced excitations have been calculated in the framework of the first Born approximation. Good agreement is found between the different computational models and fair agreement is found with prior experimental results.