Overall, for all considered test cases we find a good correlation between the coupling constants predicted by the GLDP and TDC models and the quantum-chemical reference values. For the isolated polypeptides (see Fig. and Table ), we notice that there are some distinct systematic errors for the different test cases. For the α-helix, all couplings are slightly underestimated by the vibrational maps, which is reflected by the MEs of -1.11 and -0.92 for the nearest neighbor and second neighbor couplings, respectively. For the polyalanine β-hairpin, the nearest neighbor couplings between 2 and 5 cm -1 appear to be systematically overestimated, while for the polyalanine 3 10 -helix, they feature a bimodal distribution in which some couplings are systematically underestimated by the Except for Trpzip2, the RMSD of the nearest-neighbor and second-neighbor coupling constants is smaller than 1 cm -1 for all test cases, and the coefficient of determination R 2 is larger than 0.86 and 0.94 for the first and second nearest-neighbor couplings, respectively.