The input files are intended for use with VASP density functional theory code (https://www.vasp.at/wiki/index.php/The_VASP_Manual) with pseudopotentials included within VASP. 

References for VASP are as follow: [1] G. Kresse and J. Hafner, Phys. Rev. B 47 , 558 (1993); ibid. 49 , 14 251 (1994). [2] G. Kresse and J. Furthmüller, Comput. Mat. Sci. 6 , 15 (1996). [3] G. Kresse and J. Furthmüller, Phys. Rev. B 54 , 11 169 (1996). [4] G. Kresse and J. Hafner, J. Phys.: Condens. Matt. 6, 8245 (1994). [5] G. Kresse and D. Joubert, Phys. Rev. 59 , 1758 (1999). 

The Phonopy code was used to generate atomic displacements corresponding to the phonon eigenmodes. Phonopy is available here: https://phonopy.github.io/phonopy/qe.html and references to it are: Atsushi Togo, Laurent Chaput, Terumasa Tadano, and Isao Tanaka, J. Phys. Condens. Matter 35, 353001-1-22 (2023) “First-principles Phonon Calculations with Phonopy and Phono3py”, Atsushi Togo, J. Phys. Soc. Jpn., 92, 012001-1-21 (2023)