This is an example of Elk interface.

To create supercells with displacements:

% phonopy --elk -c elk-unitcell.in -d --dim="2 2 2"

A perfect 2x2x2 supercell (supercell.in) and one 2x2x2 supercells
(supercell-xxx.in) of the conventional unit cell written in elk-unitcell.in
are created. In addition, disp.yaml file is created. After force
calculation with the crystal structure in supercell-001.in, it is
needed to create FORCE_SETS file by

% phonopy --elk -f INFO.OUT

Here INFO.OUT file is the output of the Elk calculation and is
supposed to contain the forces on atoms calculated by Elk (tforce = .true.).
The disp.yaml file has to be put in the current directory. Now you can run
phonon calculation, e.g.,

% phonopy --elk -c elk-unitcell.in -p --dim="2 2 2" --pa="0 1/2 1/2 1/2 0 1/2 1/2 1/2 0" --band="1/2 1/2 1/2 0 0 0 1/2 0 1/2"
