Electron-Ion Collisional Approach In The Study Of Rydberg And Doubly-Excited Electronic States Of H-2 And Heh+

The halfium model combines the eigenchannel R-matrix method and the generalized multichannel quantum defect theory in prolate spheroidal coordinates to characterize Rydberg and doubly-excited states of two-electron molecular systems from first pricnciples. The background picture for the model is a collisional process between the outermost (Rydberg) electron on the ionic core. Various applications to molecular hydrogen and hydrohelium ion will be shown.