This is an example to calculate phonon with possible symmetry breaking bycollinear magnetic moments. Supercells with displacements can be created by running following command:

% phonopy -d --dim="2 2 2" --magmom="1 -1" -c POSCAR-unitcell

A file named "MAGMOM" is created together with supercell POSCARs. In the MAGMOM file, a line of MAGMOM is written, which can be used in VASP INCAR. Running force calculation (350 eV, 0.1 eV smearing, 20x20x20 k-points for unit cell), we obtain vasprun.xml. With this, FORCE_SETS is created by

% phonopy -f vasprun.xml

Then phonon calculation is achieved by, e.g.,

% phonopy --dim="2 2 2" --pa="-1/2 1/2 1/2 1/2 -1/2 1/2 1/2 1/2 -1/2" -c POSCAR-unitcell --band="1/2 -1/2 1/2 0 0 0 1/4 1/4 1/4" --magmom="1 -1" -p

In the phonon calculation, magmom option has to be specified to correctly recognize the symmetry breaking.
