Ab Initio calculation of the vibrational spectrum and thermodynamic   properties of rhombohedral P4O10
  Plane-wave pseudopotential methods and density functional perturbation theory are used to calculate the phonon density of states and thermodynamic functions of h-P4O10. The calculated vibrational spectrum is in good agreement with the measured spectrum, but the calculations indicate some modifications in the interpretation of the spectrum, mainly suggesting changes in the number of components used to fit a few of the observed peaks. The calculated low-temperature heat capacity is in good agreement with the measured heat capacity, with a systematic offset of approximately -5 J mol-1 K-1, independent of temperature. . Comparison with molecular calculations indicate that molecular contributions make up about 80% of the heat capacity of h-P4O10 
James R. Rustad
cond-mat.mtrl-sci