It is clear that the dynamics included in the MD calculations are important in interpreting the measured spectral parameters at these low frequencies, both in terms of peak position but also relative peak intensity. The differences upon the inclusion of disorder into the calculation are subtle, but it should be noted that the changes between the experimental spectra recorded at 293 K and 83 K is small, particularly given the likely change in intermolecular hydrogen bonding that has been shown through crystallography. Not withstanding this, the splitting of the peak centered around 100 cm -1 in the disordered calculation, coupled to the changes in relative intensity of peaks that this leads too, suggests that the terahertz spectra of Form I is sensitive to the disorder known to exist in Form I.