Abstract

The strong interactions between simultaneously-excited electrons require nonperturbati ve theoretical techniques for their successful description. Two such nonperturbative techniques which have been pursued vigorously in recent years are the adiabatic treatment in hyperspherical coordinates and the R-matrix method. Of these, the hyperspherical treatment, which singles out the total electronic moment of inertia as an adiabatic coordinate, has been more valuable in providing a visual picture of the global evolution of electron correlations in energy and radius. The R-matrix method has evolved instead into a simple, efficient, and accurate procedure for quantitative calculations of photoionization and scattering processes. To date, however, the applications of this finite-volume variational method have been restricted primarily to the lower-lying doubly-excited channels of any given atom or molecule.

© 1986 Optical Society of America