Quantum-chemical calculations for polypeptides and small proteins provide a way of accessing (harmonic) vibrational frequencies and normal modes for specific molecular structures. By performing a localization of the relevant normal modes (i.e., the amide I vibrations) , one can reconstruct a picture in terms of the local oscillators that form the basis of vibrational exciton models. This local-mode picture can be directly related to vibrational exciton models and allows one to extract local-mode frequencies as well as coupling constants. These, in turn, can be directly compared to those predicted by vibrational frequency maps.