Considering only a small number of well-selected conformers is crucial to be able to compute IR, Raman and ROA spectra with accurate QM-based methods. In this section and the next ones we investigate whether the developed approach for the prediction of CD fingerprints can be transferred also to these other spectral observables. The computed IR spectra for the to hydrogen bonding of the C=O in the amide bond between proline and asparagine with the N-H group in the amide bond between serine and histidine (N-terminus). Cluster 11 presents a pronounced peak at 1644 cm -1 , which can be attributed to a partially α-helical structure, and two shoulders at 1612 cm -1 and 1669 cm -1 . Indeed, the experimental amide I' signal also shows prominent shoulders at wavenumbers lower than 1670 cm -1 , which most probably stem from intramolecular hydrogen bonding in microstates with ordered secondary structures, as mentioned above (Fig. and related text). Additionally, the precise amide I' shape is determined also by the hydrogen bonding pattern with water (cf. ESI section Microsolvation and ESI Fig. and). By considering the evolution of the weightedaveraged IR spectrum by increasing the number N of central structures (Fig )), we find little impact on the band position and intensity for the amide I signal. Regarding the amide II' band, a much higher variability is found among the central cluster structures. However, the weighted average progressively approaches the shape of the experimental signal. Therefore, a rational consideration of the most important conformations assumed by the peptide in solution is essential in describing the ensemble-averaged IR signal. A good convergence with N is observed by looking at the ratio of the maximum intensities between the amide I' and amide II' main peaks (Fig ), although the ratio remains overestimated in comparison with the experiment. In conclusion, our approach is able to reproduce reasonably well the overall IR band shapes, especially of the amide II' band, but not some of the minor features and the precise peak ratio observed in the experiment. This suggests that including a larger number of ordered conformers, better quantifying the conformational degrees of freedom of the side chains, or explicit inclusion of solvent may be required to further improve the agreement.