this directory contains phonopy input files for the three grain boundaries
calculations proceeds as normal until VASP POSCAR files are generated
v2met_phon_script converts the phonopy POSCAR displacements into metadise input files
metadise is then run to generate force constants for each displacement
phonopy is then used as normal to gather force constants and generate phonon modes
phonon modes are processed as described in the SI to obtain those which match the HFACF