Phonon contribution to heat capacitance of nanolayered crystalline structures

Abstract

The paper presents the innovated method of two-time dependent Green's functions applied to the bounded and translational perturbed systems. Film-structures and superlattices were analyzed by employing the phonon spectra for the calculation of relevant thermodynamic characteristics. Free energy and the internal energy of the system were found as well as the temperature behavior of layered structures. Heat capacitances of these nanostructures were compared to bulk ones. It was shown that heat capacitances of nanolayered structures in low-temperature region were higher than the same quantities of the corresponding bulk sample. In the middle and the highest temperature region, temperature behavior was inverse: heat capacitance of layered structures was lower than of the corresponding bulk ones. The consequences were discussed with relation to the (super)conductive properties of nanomaterials.