# Features

## Band structure

Phonon band structure is calculated for the specified band paths.
See Band structure tags.

## Density of states

Total and partial density of states are calculated based on the
*q*-point sampling mesh (Phonon density of states (DOS) tags). Smearing parameter
is set by SIGMA tag or `--sigma`

option.

## Group velocity

Phonon group velocity is calculated from first derivative of dynamical
matrix. See Group velocity.

## Thermal properties

Helmholtz free energy, heat capacity at constant volume, and entropy
at temperatures are calculated from the phonon frequencies on the
*q*-point sampling mesh. See Thermal properties related tags.

## Thermal properties at constant pressure and thermal expansion

Gibbs free energy, heat capacity at constant pressure, and thermal
expansion are calcualted with quasi-harmonic approximation. See
Quasi harmonic approximation.

## Measure of how far atoms move at finite temperature

How far atoms are displaced from their equilibrium positions at
temperatures is calculated as mean square displacements. See
Thermal displacements.

## Calculation of mode Grüneisen parameters

A script `gruneisen`

is used for calculating mode Grüneisen
parameters in band structure style and mesh sampling style. See the
details at Calculation of mode Grüneisen parameters.

## Normal mode analysis

Irreducible representations are assigned using polarization vectors of
phonon normal modes
(Characters of irreducible representations). Atomic displacements
corresponding to the real part of the polarization vectors are
obtained (Create modulated structure). This may be
applied for research of the second-order like structural phase
transition.

## Plot and output

The results of DOS, PDOS, band structure, and thermal properties are
immediately plotted by specifying `-p`

option
(Graph plotting). When `-s`

option is set together with the
`-p`

option, the plot is stored in the PDF file
(-p -s). In addition those results are saved
in output text files (Output files), too.