For the three isotopomers considered in this study, the anharmonic corrections do not substantially change the relative intensities of the different fundamental bands below 2000 cm–1. In this region, the main improvements arising from the anharmonic treatment is in the calculated vibrational frequencies, as discussed in the previous section. This observation is in agreement with the findings of Bloino and Barone38 using the GVPT2 approach with numerical calculation of the anharmonic IR spectra for a series of molecules.