The Ps^- ion and e^--Ps Scattering

There exists a discrepancy between a prior calculation for the photodetachment cross section of Ps^- using variational wave functions [1-3] with calculations that use the close-coupling [4] and hyperspherical close-coupling [5] wave functions. In preparation for calculating the photodetachment cross-section of Ps^-, we have used a Hylleraas-type trial function to determine the ¹S bound-state energy of Ps^-. We have determined the ¹P phase shifts for e^--Ps scattering using the inverse Kohn variational method and a trial wave function with Hylleraas-type terms. We have also computed the ^1,3S and ³P phase shifts and parameters for the ¹S, ¹P, and ³P resonances. Our calculations are an extension of prior work [1-3]. We have re-optimized the nonlinear parameters and mostly increased the number of linear parameters in the trial wave functions.