  Electron-impact ionization cross sections for the 1s2s 1S and 1s2s 3S
metastable states of Li+ are calculated using both perturbative distorted-wave
and non-perturbative close-coupling methods. Term-resolved distorted-wave
calculations are found to be approximately 15% above term-resolved R-matrix
with pseudostates calculations. On the other hand, configuration-average
time-dependent close-coupling calculations are found to be in excellent
agreement with the configuration-average R-matrix with pseudostates
calculations. The non-perturbative R-matrix and close-coupling calculations
provide a benchmark for experimental studies of electron-impact ionization of
metastable states along the He isoelectronic sequence.
