Many-body calculation of total and partial photoionization cross sections in atomic nitrogen

Abstract

Polarizabilities and photoionization cross sections are computed for the 4So ground state of atomic nitrogen. The present method is based on the use of basis sets and on an integral equation (dispersion relation) that relates the real polarizability on the imaginary frequency axis to the photoionization cross section. Many-body perturbation theory is used to compute the polarization and the perturbation expansion is complete to second order in the Coulomb interaction. Hence, there is a comprehensive inclusion of correlation effects in our calculations. Comparison with other theory and experiment is made.