A study has been made of the polarized-orbital method (POM) for electron-atom scattering. Within this framework, an exact calculation has been carried out for the electron-helium-atom case. Our study confirms the importance of the second-order distortion-exchange terms, which provide a nonadiabatic effect. A study is made of the much-criticized step function, and its inclusion within the POM framework is found to be not crucial. An attempt is made to clear up some of the present confusion in the literature by distinguishing between the POM and related methods.

• Received 10 September 1970

DOI:https://doi.org/10.1103/PhysRevA.4.1935