
PHONON Software ver.6.10 / 6.11 / 6.12 / 6.13 / 6.14 /
6.15
PHONON Software ver.5.10 / 5.11 / 5.12
Temperature of solids is almost entirely determined by phonons.
Phonons, in turn, are defined as a combination of atomic vibrations.
Small atomic vibrational amplitudes lead to low temperature of the material.
High amplitudes involve high temperature.
Since the ambient temperature is always finite,
all atoms of the whole world vibrate all the time. Thus, phonons are everywhere in solids.
Temperature dependence of any quantity of solid involves always phonons.
To name only a few: phonons are responsible for thermal expansion,
phonons contribute to appearance of phase transitions, and phase diagrams,
phonons play a role in elastic and dielectric constants, transport processes,
such as diffusion and chemical reactions, catalysis,
superconductivity, ferroelectricity, shape memory alloys, etc.
Moreover, phonon properties can be substantially modified when the crystal
is decorated by defects, like additional atoms, precipitates, interfaces, grain
boundaries, or surfaces.
Phonons are specified in the lattice dynamics theory. This theory, due to
fast and powerful computers, allow to calculate phonon characteristics using
firstprinciple or ab initio methods. At present phonons in many systems, can be
computed without any adjustable parameters. Hence, the calculated lattice dynamics
becomes a complementary tool to the measurements.
The Phonon Software allows to calculate the phonon characteristics. As an
input this software requires to know (i) a crystal structure, and (ii) a file of
HellmannFeynman forces.
External ab initio program like
VASP,
Wien2k,
MedeA of Materials Design, or
Siesta can be used in this respect.
The Phonon Software plots the dispersion curves, phonon density of states,
thermodynamical functions, neutron and xrays spectroscopic spectra,
and many others quantities. With additional calculations of effective charges
and dielectric constant the infrared and Raman spectra can be determined for
variety of experimental geometries.
