Thermodynamic characteristics up to the melting point and phonon density of states of Al.sub.3

The work presents results of research on a set of important characteristics of the molecular crystal Al(C.sub.11H.sub.19O.sub.2).sub.3 based on experimental heat capacity data. The heat capacity was measured in the temperature range 299-432 K. The isobaric thermodynamic functions (entropy, enthalpy and reduced Gibbs energy) were calculated. The phonon density of states g([omega]) was calculated using high-precision data on low-temperature heat capacity. Using the information about g([omega]), the isochoric thermodynamic functions (heat capacity, entropy, internal energy and reduced Helmholtz energy) in the range 0-494 K were calculated. Molar zero-point energy, total enthalpy and internal energy of Al(C.sub.11H.sub.19O.sub.2).sub.3 were determined. The knowledge of zero-point energy is very important when considering the energy balance of the solid and can be used to investigate the stability of the crystal lattice. All obtained characteristics were evaluated for accuracy.