Electron-Impact Ionization from Excited States in H-Like Ions

To test the validity of classical trajectory and perturbative quantal methods for electron-impact ionization of H-like ions from excited states, we have performed advanced close-coupling calculations of ionization from such states in H, Li$^{2+}$, and B$^{4+}$ using the R-matrix with pseudo states (RMPS) and the time-dependent close-coupling (TDCC) methods. We will show comparisons of the results of our RMPS and TDCC calculations with those from our classical trajectory Monte-Carlo (CTMC) and distorted-wave (DW) calculations; these comparisons demonstrate that the CTMC method is more accurate than the DW method for H, but does not improve with $n$ and grows substantially worse with $Z$, while the DW method improves with $Z$ and grows worse with $n$.