Freq (cm When the distance is 5 Å, although QM/DIM slightly underestimates the intensity of mode 12, it nearly reproduces the full QM spectra as Figs. ), 3(e), and 3(f) show. As R decreases, however, QM/DIM gives less satisfying Raman profiles. Taking Py-Au 18 -V system with R = 4 Å as an example (see Fig. )), we observe that QM/DIM significantly underestimates the intensity of mode 12 but overestimates this of mode 11 compared with the full QM results. When R is further shortened to 3 Å, the discrepancy between full QM and QM/DIM results in all frequency ranges increases. As shown in Table , QM/DIM significantly overestimates the intensities of all the modes except mode 12. In other words, the QM/DIM approach could provide artificial enhancements for some vibrational modes, which can be attributed to the neglect of chemical enhancement and nonlinear responses of the MNP in the current QM/DIM model.