Phonons are the fundamental vibrational objects in solid state materials, and to large extend they define the finite temperature properties of solids.

Phonons are present in any material. They are the driving forces for quite a number of phenomena mentioning only the thermal expansion, heat conductivity, temperature dependence of mechanical, electric properties, phase transitions. They also enhance the diffusion. They occur in bulk crystals, surface, interfaces, multilayers, crystals with topological defects and impurities.

Phonons play a crucial role in several picturesque phenomena, like superconductivity, ferroelectricity, displacive phase transitions, shape memory alloys, etc.

Phonons play an important role for quite a number of microscopic and bulk phenomena such as inelastic coherent and incoherent neutron scattering, coherent inelastic x-ray scattering, inelastic nuclear absoprtion, infrared absorption, raman scattering, thermodynamical functions, Debye-Wller factor temperature dependence of mechanical properties, and even chemical reactions. Therefore, it is evident that a deeper understanding of phonon behavior, specially for the new materials, is a necessary condition for the future further technological development.

Thanks to the theoretical advances, it is possible now to consider the phonon dynamics calculations as a complementary tool to the experiment. Moreover, the calculations allow for animation of phonon modes and visualization of phonon waves.

In this web page a few crystalline models are considered and the selected phonon modes can be animated directly on the screen. The representative atomic motion involved in a phonon can be visualized by selecting: - a model and - a phonon (dot on the phonon dispersion curves).

Animation were prepared within diploma thesis of:
Bogdanik Lukasz, Cwiek Piotr, Gis Krzysztof, Grzywa Grzegorz, Iwanski Daniel, Sulkowski Piotr, Tarko Pawel, and Wozniak Pawel
written at the Pedagogical University in Cracow, Poland, under supervision of Prof.Krzysztof Parlinski, using the Software PHONON.

We acknowledge the use of programs Molekel ver. 4.3 [1,2] and GIF Movie Gear 2.52 with which the animations were prepared.
References: [1] P.Fluekiger, H.P.Luethi, S.Portman and J.Weder, Software MOLEKEL 4.3,
Swiss Center for Scientific Computing, Manno, Switzerland, (2000-2002).
[2] S.Portamn and H.P.Luethi, Chimia 54, 766 (2000).