The experimental liquid-phase spectrum of CH2DNO2 from ref. 81 is reproduced in Fig. 8 for comparison. A major improvement in comparison to the experimental spectrum is observed when including anharmonic corrections for the splitting of the 31 band with respect to the position of the deuterium atom, around 2195 cm–1 if the CD bond stretches almost parallel to the NO2 plane and around 2295 cm–1 if it stretches almost perpendicular to it, as seen in the experimental spectrum. A weak peak appears in the anharmonic spectrum around 2250 cm–1, corresponding to the 61111 combination band, mainly from the D-eclipsed rotamer. Another weak feature appears around 2310 cm–1, corresponding to the 8191 combination band present in all the four rotamers.