A relativistic approach to the elastic scattering of electrons by argon

Phase shifts and total and differential cross sections are calculated for the elastic scattering of unpolarised electrons by argon atoms in the impact energy range of 0.1 to 40 eV. The target atom is represented by a frozen core in a continuum relativistic Hartree-Fock calculation with dipole and quadrupole polarisation corrections. Exchange is calculated exactly and the parameters of the model polarisation potential are fixed by independent calculations. The results are in good agreement with experiment and with some of the non-relativistic coupled Hartree-Fock calculations; they demonstrate the importance of core polarisation effects as well as of relativistic effects at low incident energies.