Ground state and resonance state of Ps− in plasmas with various Debye lengths

We have made an investigation on the resonances for positronium negative ion Ps^- in various model plasma environments. The 2s²0.2em0ex¹Sᵉ autoionization resonance state in Ps^- ion is determined by calculating the density of resonance states using the stabilization method. We have also performed accurate variational calculations to obtain ground-state energy eigenvalues of Ps^- for various Debye lengths. A screened Coulomb potential obtained from the Debye model is used to represent the interaction between the charged particles. A correlated wave function has been used to represent the correlation effect between the three charge particles. The calculated resonance energies and widths for various Debye parameters ranging from infinity to a small value along with the ground-state energies are reported.