SCHWINGER'S VARIATIONAL PRINCIPLE FOR ELECTRON-ION SCATTERING.

摘要

Schwinger's variational principle (J. Schwinger's lecture notes at Harvard University, 1947) is formulated for electronion (atom) collision using the coulomb (free particle) Green's function. The theory is applied to a screened coulomb potential as well as e('-) - He('+) and e('-) - H to obtain analytic distorted waves, phase shifts, and quantum defects for energies near the ionization threshold. A numerical technique of calculating the phase shifts and wave functions is also outlined.