Vibrational frequency maps for the amide I region are commonly validated by comparison to experimental infrared and 2D-IR spectra, either for small model systems such as NMA , or by applying them in the calculation of 2D-IR spectra of polypeptides of proteins . While they generally do show a good accuracy in such a com-parison, such an approach is rather indirect and prone to error compensation. Spectra simulated using vibrational exciton models depend on the interplay of all different parts of the vibrational frequency map (such as the different contributions to the local frequencies as well as the coupling constants) simultaneously, and it is not possible to trace back differences between simulated and experimental spectra to specific components of the model.