(a) MeOH -H + -HOMe Wavenumber / cm In ensi y / a.u. Wavenumber / cm In ensi y / a.u. Wavenumber / cm In ensi y / a.u. In contrast, the peak positions and intensities from both CNEO-DFT without electronproton correlations and CNEO-DFT with the epc17-2 functional align much more closely with the experimental IR spectra. Normal mode analysis shows that many peaks in the range of 800 to 1100 cm -1 have proton transfer characters. For example, in Fig. show that in MeOH -H + -HOMe, proton transfer is involved in multiple normal modes. The frequencies and relative intensities of the these modes generally agrees well with experimental results. However, a major discrepancy is that in all four systems, the peak slightly below 1600 cm -1 is too intense compared with experimental results. The reason for this discrepancy is unclear, as these peaks are also mainly associated with proton transfer, and no peaks are dominated by O-H-O bending.