Phonon share to the thermal capacitance of ultrathin crystalline film along the entire temperature region.

As a result of theoretical considerations on the study of the influence of the phonon quasiparticle subsystem on the thermal capacitance of a two-dimensional quasicrystal in the form of an ultrathin film, an exact formula for the thermal capacitance of an ideal ultrathin film, valid over the entire temperature range, is derived in this paper. The dispersion equation as well as the possible phonon energies and allowed phonon states were determined by the method of Green's functions. The obtained formula for the thermal capacitance of the ultrathin film is plotted and compared with the corresponding graphs representing massive crystalline structures in both the low-temperature and high-temperature regions. The conclusions that can be drawn are highly consistent with recent results related to the possibility of realizing high-temperature superconductivity. [ABSTRACT FROM AUTHOR]