CROSS-SECTIONS FOR ELECTRON-SCATTERING BY ATOMIC POTASSIUM

Electron elastic and collisional excitation cross sections from the ground state of potassium are calculated using the noniterative integral-equation method of Henry, Rountree, and Smith [Comput. Phys. Commun. 23, 233 (198 1)] in the electron energy range 4 less-than-or-equal-to E less-than-or-equal-to 200 eV. Configuration-interaction target wave functions that take account of correlation and polarization effects are used to represent the ground state and the six lowest excited states 4p2P-degrees, 5s2S, 3d2D, 5p2P-degrees, 4d2D, and 6s2S. Elastic and discrete excitation cross sections are obtained in a seven-state close-coupling (7CC) approximation. The 7CC elastic and excitation cross sections are compared and contrasted. Near threshold the elastic cross section dominates the resonance, 4s2S --> 4p2P-degrees, and the sum of the other remaining excitation cross sections. Comparison of our total cross sections with some available experimental and theoretical data is also effected. The discrepancy between the recent measurement of the total cross section by Kwan et al. [Phys. Rev. A 44, 1620 (1991)] on the one hand and other measurements near threshold on the other hand is explained.