Electron-impact ionization of highly excited hydrogenlike ions in a collinear s-wave model

We report results from collinear time-dependent close-coupling TDCC , distorted-wave DW , and R matrix with pseudostates calculations for the electron-impact ionization of H-like ions up to Z=6 within an s-wave model. We compare the results of these calculations with those from a collinear classical trajectory Monte Carlo calculation to investigate the correspondence between the quantal and classical ionization probabilities as the principal quantum number of the initial state increases. In these model calculations, the electron-electron interaction is represented by the collinear s-wave potential given by 1/ r1+r2 . We study the ionization probability from the ground state and highly excited states up to n=25 as a function of incident energy and the charge of the ion. We show that the fully quantal ionization probability converges to the classical results rapidly for hydrogen. The higher ion stages exhibit much slower convergence with respect to n. We observed good agreement between the DW and TDCC for the n range we have considered for B4+. For hydrogen, we found fairly good agreement between the DW and TDCC for the ground state, but the worsening disagreement with increasing n. There is reasonable agreement between the results from the R-matrix calculations and the results from the TDCC calculations confirming the convergence of the TDCC results.