Positron impact excitation of lowest autoionizing state of potassium atom using distorted wave method with absorption and polarization potentials

Abstract

Differential and integral cross-sections, as well as the alignment and lambda parameters for positron impact excitation of the lowest autoionizing state of potassium atom, have been calculated using a non-relativistic distorted wave method in the energy range of 18.9–1500 eV. The distortion potential in the initial and final channel state comprises a linear combination of static potential plus polarizationand absorption potentials. The approximate Roothan-Hartree–Fock (RHF)wavefunctionsMulti zeta wavefunctions given by Clementi and Roetti have been used. The inclusion of polarization and absorption potentials has improved integral cross-section and alignment parameter results. The integral cross sections have shown the near threshold resonance structure revealed in electron impact excitation experimental results. Differential cross-section and lambda parameter results have been calculated and presented for future comparison since there are no other results available in the literature for positron impact excitation.