PHOTOIONIZATION OF 2-ELECTRON ATOMS VIA THE HYPERSPHERICAL ARTIFICIAL-CHANNEL METHOD - APPLICATION TO H- AND HE

An application of the artificial-channel method with hyperspherical co ordinates to the calculation of photoionization cross sections of two- electron systems is presented. The method yields ''bound-free'' transi tion amplitudes and bound-state energies of any two-electron system. I t obviates the separate generation of bound- and continuum-state wave functions by calculating directly the desired amplitudes. As applicati ons, the photodetachment cross section of the H- ion and the photoioni zation cross section of the He atom have been calculated. The computat ions are compared with other theoretical calculations and with experim ents. The results obtained are in excellent agreement with experimenta l results for all the energies considered. Of equal significance is th e close agreement, attesting to the high accuracy of the method, betwe en results obtained by using the length form for the field-matter inte raction and those obtained with the acceleration form.