Another obvious discrepancy in the TDHF electron dynamics from the ideal Rabi behavior is in the frequency of oscillation and here we find a strong size-dependent trend. We can quantify the trend by comparing the Rabi frequencies, using linear response transition dipole moments (Table ), and those deduced from the oscillations of time-dependent LUMO occupations for applied electric fields with differing amplitudes, see Table . For System 1 in the presence of the weakest field applied here, E max =0.001 a.u., the observed population oscillation has a frequency of 1.6 × 10 -3 , whereas that calculated is 4.6 × 10 -3 , yielding a deviation of ∼180%. The deviation decreases to ∼75% with the stronger field of E max =0.005 a.u. The agreement in the oscillation fre-quency is improved with increasing system size, going to deviations of ∼125% and ∼100% for Systems 2 and 3 with E max =0.001 a.u. and ∼35% and ∼25% for Systems 2 and 3 with E max =0.005 a.u. Overall, the trend suggests that the errors in transfer of electron density between S 0 and S 1 in the presence of a resonant field tend to decrease with increasing system size, implying potentially a similar increase in accuracy in charge-transfer dynamics.