#
**PHONON ** Software

###

by Krzysztof PARLINSKI

* Last update: January 2, 2008*

** Phonon** is a software (see list of Publications)
for calculating phonon
dispersion curves, and phonon density spectra
of crystals, crystals with defects, surfaces, adsorbed atoms on
surfaces, etc. from either a set
of force constants, or from a set of Hellmann-Feynman forces calculated
within an *ab initio*
program (not included).
One can use
VASP,
Wien2k,
MedeA of Materials Design
,
Siesta, or other *ab initio* code
which is able to optimize a supercell and calculate the Hellmann-Feynman forces.
**Phonon** builds a crystal structure, using one of the 230
crystallographic space groups,
finds the force constant from the Hellmann-Feynman forces, builds the
dynamical matrix, diagonalizes it,
and calculates the phonon dispersion relations, and their intensities.
**Phonon**
finds the polarization vectors, and the irreducible representations
(Gamma point) of phonon modes,
and calculates the total and partial phonon density of states.
It plots the
internal energy, free energy, entropy, heat capacity
and tensor of mean square displacements (Debey-Waller factor).
**Phonon** finds the dynamical structure
factor for the coherent inelastic neutron scattering and the incoherent
doubly differential scattering cross section for a single crystal and
polycrystal.
For polar cystals the LO/TO mode splitting can be included.

**DemoPhonon** demonstrates the full functionally of **Phonon**,
but is limitted to a single space group Fm3m.

##### See: