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, aswell as the alignment and lambda parametersfor 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 andfinal 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 nearthreshold resonance structure revealed in electron impact excitation experimental results. Differential crosssection and lambda parameter results have been calculated and presentedforfuture comparison since there are no other results available in the literaturefor positron impact excitation