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phonoLAMMPS

Calculate the harmonic interatomic force constants using phonopy and LAMMPS.
Online manual: https://phonolammps.readthedocs.io

Main features

  • Command line interface (phonopy like style)
  • Python API fully compatible with phonopy
  • Use of official LAMMPS python interface
  • Simple and easy to use
  • Finite temperature force constants using DynaPhoPy

Requirements

Optional requirements for phonon band structure preview

Optional requirements for finite temperature FC calculations

Optional requirements for tinker

Installation instructions

  1. From source code
# python setup.py install --user --prefix=
  1. From PyPI repository
# pip install phonoLAMMPS --user

For convenience, you may want to copy (or link) the files inside scripts folder to a location included in $PATH environment variable

Command line interface

phonoLAMMPS has a similar interface to phonopy to allow to easily calculate the 2nd order force constants and generate the crystal unitcell from a LAMMPS input file in VASP/POSCAR format. All outputs are fully compatible and ready to use in phonopy calculations. Also features a quick preview of the phonon band structure (requires seekpath).

# phonolammps in.lammps --dim 2 2 2 -c POSCAR_unitcell -p

Additionally phonoLAMMPS allows to easily calculate finite temperature force constants from molecular dynamics by quasiparticle theory (requires dynaphopy).

# phonolammps in.lammps --dim 2 2 2  -c POSCAR_unitcell -p -t 300       (at 300 K)

The obtained FORCE_CONSTANTS and POSCAR_unitcell can be used in phonopy using --readfc option for more advanced calculations.

# phonopy --dim="2 2 2" --readfc -c POSCAR_unitcell band.conf

Python API

Simple python API fully compatible with phonopy.

from phonolammps import Phonolammps
from phonopy import Phonopy

phlammps = Phonolammps('in.lammps',
                       supercell_matrix=[[3, 0, 0],
                                         [0, 3, 0],
                                         [0, 0, 3]])

unitcell = phlammps.get_unitcell()
force_constants = phlammps.get_force_constants()
supercell_matrix = phlammps.get_supercell_matrix()

phonon = Phonopy(unitcell,
                 supercell_matrix)

phonon.set_force_constants(force_constants)
phonon.set_mesh([20, 20, 20])

phonon.set_total_DOS()
phonon.plot_total_DOS().show()

phonon.set_thermal_properties()
phonon.plot_thermal_properties().show()

Contact info

Abel Carreras
[email protected]

Donostia International Physics Center (DIPC)
Donostia-San Sebastian (Spain)