Photoabsorption cross sections of two‐electron atoms by the coordinate rotation method: Application to H⁻ and several states of He 

The coordinate rotation method, recently extended by us to treat photoabsorption processes, is used to obtain photoabsorption cross sections for several two‐electron atoms. The calculations are performed using standard configuration–interaction methods; the need for atomic continuum wavefunctions is completely avoided in this approach. We have computed the photodetachment cross section of H⁻ and photoionization cross sections for He in its ground and 2 ¹S states. In all cases, the computed cross sections agree well with results obtained by numerical integration and with available experimental data.