The resulting spectra are shown in Fig. , with comparison given to the spectra computed from a trajectory with the electron density perturbed with a delta-kick electric field. The LR-TDHF S 0 → S 1 excitation energies are also shown in the spectra for reference, with the LR-TDHF energies being in excellent agreement with the delta-kick absorption spectra peaks. For all three molecules, the spectra generated from the single electron occupation show significant shifts from that obtained with the deltakick pulse, in violation of the resonance condition. The peak shifts to lower energies by 0.85 eV, 0.62 eV, and 0.57 eV for Systems 1, 2, and 3, respectively, showing a decreasing shift with larger system size. In previous studies of TDDFT peak shifting in small model molecular systems, the direction and magnitude of the peak shift was found to be directly related to the S 1 → S 2 transition energy, where the S 0 → S 2 transition was dark and the S 2 state was predominantly a doubly occupied LUMO. The S 1 → S 2 peak became coupled to the S 0 → S 1 peak as the LUMO occupation grew. With the relatively larger systems considered here it is difficult to characterize a similar S 2 state, but with an estimate of the energies given by the SA-CASSCF method, we know that the energy of the S 1 → S 2 transition is likely smaller than the energy of the S 0 → S 1 transition, causing a shift to lower energies. Additionally, just based on the relative energies of the SA-CASSCF S 0 → S 1 and S 1 → S 2 transitions, we would also expect a decrease in the degree of peak shifting with increasing system size. Overall, we find that the magnitude of the peak shift is significant, but it does indeed decrease as the system size increases, which may be due to the relative energies in the chosen molecules or due to larger systems being less subject to errors due to the adiabatic approximation.