THEORETICAL-STUDY OF THE VALENCE AND CORE PHOTOIONIZATION OF A 3-ELECTRON SYSTEM FROM LITHIUM TO NEON

The multiconfiguration Hartree-Fock (MCHF) method for continuum wavefu nctions is used to study the photoionization of lithium and ions of it s isoelectronic sequence for photon energies from 0.1 to 250 Ryd. Elec tron correlation and polarization effects in the initial and final sta tes and relaxation and correlation in the final ionic stales, which ar e found to be very important in the valence- and K-shell partial photo ionization cross sections, have been taken into account accurately in an ab initio manner through the configuration interaction procedure. T he present results are compared with available experimental measuremen ts and accurate theoretical data for a limited energy range and are fo und to be in good agreement.