Theoretical Approach to the Calculation of Energies and Widths of Resonant (Autoionizing) States in ManyElectron Atoms
Abstract
A theoretical approach, capable of providing quantitative results for Nelectron nonrelativistic "nonstationary" states is presented. I treat innerhole or doubly excited states, observed in various types of experiments, from a conceptually single point of view, as decaying states. First, the relevant important quantities already known, e.g., from Feshbach's theory, are derived and interpreted in a mathematically and physically meaningful way. Then I consider the exact squareintegrable Nelectron function describing the initial localized Nelectron state and, from straightforward variationperturbationtheory considerations, I derive a variational minimum principle which permits one to incorporate systematically the important correlation effects without the danger of a "variational collapse." This method requires projection onto known oneelectron zerothorder functions and it thus overcomes the difficulties of the wellknown P, Q methods which require projection onto exact wave functions. From preliminary Nbody calculations I find the He^{}^{2}P^{0} and ^{2}D resonances, previously observed experimentally, at about 57.3 and 58.4 eV. In addition, I predict the positions of various autoionizing states: in Li I at about 140.7 eV (a ^{2}P^{0} state), in C IV at about 306.7 eV (^{2}D), in N I at about 14.9 eV (^{2}D), and in F I at about 22.4 eV (^{2}S) above the ground state. These states, which are just samples of states treatable by this approach, may in principle cause observable structures, e.g., in photonabsorption experiments, in particleatom scattering experiments, or in beamfoil experiments.
 Publication:

Physical Review A
 Pub Date:
 December 1972
 DOI:
 10.1103/PhysRevA.6.2078
 Bibcode:
 1972PhRvA...6.2078N