The B-C bond stretches appear in the range of 1250-1400 cm -1 (area highlighted in yellow). This observation is also in line with the normal mode analysis results predicting B-C stretches exactly in this region. We observe that boroxine and phenyl fragments also show peaks in this area possibly because the B-C bonds stretches are collective vibrational modes which affect the overall structure. The peak at ≈ 1000 cm -1 (area highlighted in red) appears to result from vibrations of the phenyl ring. Normal mode analysis suggests that this peak corresponds to the aromatic C-C bending modes. Notably, the spectrum of the phenyl fragments features two peaks in the region highlighted in red, rather than the single prominent peak visible in the spectrum of the whole structure. Artificial peaks have been previously observed in AIMD-computed vibrational spectra of liquid benzene using MLWFs. This observation was explained as follows and might also apply here: Throughout the AIMD simulation, the locations of the MLWFs representing the double and single bonds of the phenyl ring interchange. This leads to spurious changes of the dipole moment, and eventually artificial bands in the spectrum. Artificial peaks can also be observed in the low-frequency region of the MD-based IR spectrum of the phenyl fragments (Figure S8, SI). However, the effect is small and does not hamper the assignment of the peaks in the overall vibrational spectra to boroxine or phenyl fragments.