Correlation-potential method for negative ions and electron scattering

The relativistic correlation-potential method was used to calculate binding energies and fine-structure intervals for Pd, Ba, and Yb negative ions and to investigate low-energy electron scattering by Yb, Hg, and Ra atoms. The results for the binding energies are the following: 540 meV for the 5s state of Pd^-, 190 and 133 meV for the 6p_1/2 and 6p_3/2 states of Ba^-, and 36 meV for the 6p_1/2 state of the Yb^-. A number of prominent p and d resonances are revealed in the scattering phase-shift calculations. These p or d resonances lead to a phenomenon of 100% polarization of the scattered electron beam at appropriate electron energy and scattering angle. A criterion is proposed to measure the strength of the nonlocal correlation potential and to evaluate its ability to create a bound state: ∫G(r',r)Σ(r, r')dr dr'>1 is the necessary condition for the formation of a bound state. Here Σ is the correlation potential and G is the electron Green's function at zero energy.