
Harmonic Phonon Software ver. 6.15.
The Harmonic Phonon Software allows
to calculate phonon dispersion
curves, irreducible representation of modes
(at Γ), phonon density of states, thermodynamic functions,
DebeyWaller factors, inelastic neutron and xrays scattering,
dielectric constant, infrared absorption and Raman scattering.
The input HellmannFeynman forces should be calculated
by a standard ab initio software, like VASP, Wien2k, or others,
which treat the considered crystal as a supercell.
Due to crystal symmetry
the HF forces should only be
calculated for several displaced atoms in the supercell.
Phonon Software can also be used for modeling the
lattice dynamics. This approach proves to be useful in order
to obtain feeling on the phonon behaviour in a given material,
since the force constants, and/or twobody spring constants
have to be guessed by the User.
Phonon is designed to calculate lattice dynamics
for crystals having one of 230 space groups, but calculations
for surfaces and multilayers in slab approach,
lattices with defects, etc. have also been done.
All calculated results are written in a collection of text files,
so that reuse, and/or replot of the data is available at any time.
Phonon Software, ver.6.15, is a further development of Phonon Software
vers.4.30, 5.12, and 6.14.
The menu of Harmonic Phonon Software ver. 6.15 contains the following options:
 Files
 New Project  initialization of a project either as
Ab initio (Ai), or Modeling (Mo) phonons.
 Open Project  activation of existing project.
 Copy Project  copy active project to another one with a different name.
 Delete Project  delete active project.
 Import Model  download from a database a project
ready to run. Structural parameters and HellmannFeynman file are included.
 Preferences  shows license, and
general option for Phonon Software appearance.
 Create
 SymmetryUnit Cell  selection of the
crystallographic space group of the project crystal,
setting of lattice constants and angles. The 230 space groups are given in
setting of either International Tables for Crystallography (1989),
or in Kovalev (1965) setting (Ai,Mo).
 Particles  construction of the crystal structure from
nonequivalent positions of atoms (Ai,Mo).
Constructed unit cells can be viewed.
Introduction of effective charges tensors
imported from (Ai) calculations can be symmetrized
to satisfy requirement of crystal site symmetries.
 Interaction Range  setting of supercell (ai,Mo), or
coordination shells (Mo) used later in derivation of the force constants
for dynamical matrix. Possible automatic update of lattice constants and atomic
positions after optimization by ab initio program (ai).
Any shape of supercell can be used. If the supercell breaks
the crystal space group then the lower space group symmetry is
accepted. Here are calculated the neighbor list, symmetry of force
constants matrices and the numbers of independent force constant
parameters (ai,Mo). A set of displacements needed to calculate the
HellmannFeynman forces for the direct method is proposed (ai). A file with
positions of all atoms of the supercell can be issued (ai).
The supercell can be viewed.
 HellmannFeynman Forces (ai)  write here the
HFFILE file of ab initio
optimization: suppercell lattice constants, requirements to impose
translationalrotational invariances, and name of HellmannFeynman file.
At this option force constant matrices are derived from the supplied
HellmannFeynman forces, collected in HFFILE,
using direct method. If needed the force constants
can be modified to fit additionally the phonon frequencies to
experimental points.
Plot of the value of the force constant elements as a function of distance
demonstrates the decay of potential interaction with distance.
 Potential Parameters (ai,Mo)  a formulae to introduce the values
of independent
parameters of the force constants by hand. For some highsymmetry crystals
Invariances option allow to impose
on force constants the translationalrotational invariances.
 Report  text file reporting results obtained while running
options under Create (ai,Mo).
 Analyze
 Dispersion Curves  first specify the wave vectors along which
the phonon dispersion curves (PDC) will be calculated.
Then, plot the PDC. The PDC can
be also plotted using colours, where the colour is defined by the intensity
involved in a phonon mode. The intensity is calculated with the aim of
polarization vectors according to separately determined filters.
With mouse a single component of phonon mode can be selected on the
plot of PDC and
the atomic vibrations in crystal supercell can be animated.
Harmonic Phonon Software has a buildin animator routine based on OpenGL.
Similarly for single mode selected with the mouse the low
symmetry space group appearing as a result of
condensation of this mode, can be found by applying the
FindSym
program of
H.T.Stokes and D.M.Hatch from Brigham Young University.
Phonon software finds the irreducible representations for all phonon modes
at the Brillouin zone center.
Another option allows to search over many Brillouin zones to find the
Brillouin zone of most intense phonon mode.
 Mode Displacements  permits to elaborate arbitrary number of
irreducible representations, including all the irreducible components
and irreducible arms,
to search for displacement pattern, symmetry reduction and animate several
phonon modes simultaneously as specified in dialogs.
 Density of States  determines plots of
the phonon density of states (DOS) and partial
phonon density of states of all atoms and all axes x, y, z
calculated by Monte Carlo sampling of the Brillouin zone.
 Thermodynamics  plots of internal energy, free energy,
entropy, heat capacity at constant volume,
all components of the the symmetric tensor
of thermal mean square displacements as a function of temperature,
and in harmonic approximation.
 Spectroscopy
 Neutron Scattering  using PDC and DOS, taking into account the corresponding
neutron scattering crosssections, the peak intensities of PDC
for coherent neutron scattering,
and incoherent inelastic scattering on polycrystals and monocrystals
are calculated
for any geometry. For incoherent scattering on polycrystals
the multiphonon correction can be added.
 Xrays Scattering  using PDC and DOS, taking into account the corresponding
atomic form factors, the peak intensities of PDC for xrays scattering,
and nuclear inelastic scattering on monocrystals are calculated
for any geometry. For nuclear inelastic scattering
the multiphonon correction can be added.
 Dielectric Properties  determines the dielectric tensor in phononic
harmonic phonons.
The mode effective charges for the Γ Brillouin zone point can be
calculated for any unit vector pointing to Brillouin zone center.
The complete
group theoretical analysis of the transverse TO and longitudinal LO optic phonon
modes is made.
 Infrared Absorption  using Born effective charges for TO and LO modes
for polarized and unpolarazed light,
the IR spectra for monocrystal and polycrystal can be determined.
 Raman scattering  are calculated using the Raman tensors.
These tensors must be calculated
within ab initio code (ai) from changes of dielectric constant
caused by a displacement
of a single atom, one at a time. This approach resembles calculations
of HellmenFeynman forces
for deriving the phonon frequencies.
 Help
 Phonon Manual  provides detailed description of all of Phonon Software options.
Last update: July 20, 2014
