TIME-DEPENDENT AND TIME-INDEPENDENT CLOSE-COUPLING METHODS FOR THE ELECTRON-IMPACT IONIZATION OF BE+

The electron-impact ionization cross section of Be+ is calculated usin g both a time-dependent and a time-independent close-coupling method. The time-dependent method is based on the propagation of wave packets constructed using excited-state orbitals calculated in a core pseudopo tential. The time-independent method is an R-matrix solution based on a total wave function constructed using antisymmetrized products of La guerre pseudo-orbitals and zero-derivative box orbitals. in both metho ds, low partial-wave close-coupling results are added to high partial- wave distorted-wave results to yield ionization cross sections for Be substantially below the experimental crossed-beam measurements of Fal k and Dunn [Phys. Rev. A 27, 754 (1983)] and in agreement with the rec ent time-independent close-coupling calculations of Bartschat and Bray [J. Phys. B 30, L109 (1997)].