Fig. 7. IR spectrum of n-butane obtained via the ML model (red), compared to the static quantum mechanical spectrum computed at the B2PLYP level (blue) and convoluted with Gaussians. The peak positions in the ML and B2PLYP spectra agree closely, suggesting that the observed deviations from the experimental spectrum (grey) are not caused by the ML approximation. The overall structure of the peaks is reproduced much better by the ML accelerated AIMD simulation, especially in the region of the C–H stretching vibrations (see inset).