Shape resonances in the electron-hydrogen system with screened Coulomb potentials

Abstract

We investigate the shape resonances of the electron-hydrogen system embedded in Debye plasma environments modeled by screened Coulomb potentials. The complex-coordinate rotation method is employed to calculate the resonance parameters and the Hylleraas-type wave functions are used to represent the correlation effects of the two electrons. The ${}^{1}{S}^{e}$ resonance states of H${}^{\ensuremath{-}}$ above the $N=2$--5 thresholds of H atom are investigated and the resonance parameters for a Debye length ranging from infinity to small values are reported. It is shown that the widths of the shape resonances lying above the H($N=4$,5) thresholds exhibit some interesting behaviors in relatively strong screening situations. The possible reason for such phenomena is discussed.