First-principles calculations of vibrational and thermodynamical properties of solids

The presented first-principle phonon calculations make use of the standard DFT program, and the direct method. The procedure requires optimization of the structure, calculation of the forces, and construction of the dynamical matrix. This method has already been applied to a large number of crystalline systems to calculate the phonon dispersion curves, phonon density of states, and thermodynamic functions, which were required for a description of phase transitions.