Critical minima in elastic electron scattering from argon

Relativistic ab initio calculations of both low- and high-angle critical minima in the differential cross sections are presented. The theoretical approach is based on the Dirac-Hartree-Fock method. Exchange between incident and target electrons is calculated exactly. Target polarization is described by ab initio potential taken from relativistic polarized orbital calculations. The position of our critical minima (39.3 eV, 68 deg.) and (39.5 eV, 141 deg.) agree well with recent measurements performed by Panajatovic et al. (author). Letter-to-the-editor