The software PHONON by K. Parlinski uses the Hellmann-Feynman forces from VASP, in order to calculate phonon dispersion relations, phonon density of states, mode symmetries, thermodynamic functions, neutron coherent and incoherent scattering, x-rays scattering, nuclear inelastic scattering, infrared absorption, and Raman scattering. PHONON can be used for crystals, crystals with defects, surfaces in slab models. One may build phase diagrams in the quasiharmonic approximation. It has scripts to/from VASP.