Resonance states of Ps- using correlated wave functions
Abstract We have investigated the F e 1 , 3 resonance states of positronium negative ion below the N = 3 , 4 and 5 Ps thresholds using highly correlated exponential wave functions. Resonance parameters (positions and widths) are extracted employing both the stabilization method and the complex-coordinate rotation method. In addition to many Feshbach resonances below the various Ps thresholds, we have identified two F e 1 shape resonances with one each lying above the N = 3 and N = 5 thresholds, respectively. We have also identified three F e 3 shape resonances with one lying above the N = 3 threshold and two lying above N = 4 threshold. The F e 1 , 3 shape resonances associated with N = 3 Ps threshold and some other Feshbach resonances are reported for the first time in the literature.
Complex-Scaling Calculations for Doubly Excited Resonances in Ps− Interacting with Screened Coulomb (Yukawa) Potentials
We have investigated the effect of screened Coulomb potentials on the high-lying doubly excited resonance states of the positronium negative ion in the framework of complex-scaling method. Highly correlated wave functions in Hylleraas coordinates are used. The resonance parameters below the Ps (2s2S) and Ps (3s2S) thresholds, for various screening parameters, are reported.
Resonant photodetachment of the positronium negative ion.
An adiabatic treatment in hyperspherical coordinates is used to predict the existence of resonant structures in ${\mathrm{Ps}}^{\ensuremath{-}}$ (Ps denotes positronium) photodetachment. This highly correlated system displays a weak series of narrow Feshbach resonances lying just below the $\mathrm{Ps}(n=2)$ threshold, while a single strong shape resonance dominates the photodetachment spectrum above this threshold as in ${\mathrm{H}}^{\ensuremath{-}}$. Use of a "prediagonalized" representation of hyperspherical harmonics dramatically improves the convergence of the adiabatic calculation.