This package contains a fix phonon command that calculates dynamical matrices from finite temperature MD simulations, which can then be used to compute phonon dispersion relations, directly from molecular dynamics simulations.

See the doc page for the fix phonon command for detailed usage instructions.

Use of this package requires building LAMMPS with FFT suppport, as described in doc/Section_start.html.

There are example scripts for using commands in this package in examples/PACKAGES/phonon.

There is an auxiliary post-processing tool in tools/phonon that will compute phonon frequencies and dispersion relations from the dynamical matrices output by the fix phonon command.

There is also an alternative code, dump2phonon, available which enables one to use the functions of fix-phonon by reading in atom-style dump files of lammps (which can be converted from the trajectories of any other MD code): https://github.com/lingtikong/dump2phonon

The person who created fix phonon is Ling-Ti Kong (konglt at sjtu.edu.cn) at Shanghai Jiao Tong University. Contact him directly if you have questions.