Phonopy

Phonopy is an open-source Python package designed for calculating phonon properties at harmonic and quasi-harmonic levels. It integrates with various first-principles density functional theory (DFT) codes, such as VASP, Quantum ESPRESSO, and ABINIT, to compute interatomic forces. Using the finite displacement method and crystal symmetry, Phonopy can derive phonon band structures, densities of states (DOS), thermal properties (free energy, heat capacity, entropy), group velocities, and more. The library is actively maintained and regularly updated, with version 3.5.0 being the current release.