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Topic: Phonon

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A phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid.
The study of phonons is an important part of solid state physics, because they contribute to many of the physical properties of materials, such as thermal and electrical conductivity.
For example, the propagation of phonons is responsible for the conduction of heat in insulators, and the properties of long-wavelength phonons gives rise to sound in solids.
www.ebroadcast.com.au /lookup/encyclopedia/ph/Phonon.html   (2148 words)

Phonons are quantized modes of vibration occurring in a rigid crystal lattice, such as the atomic lattice of a solid.
Phonons manifest themselves in all properties of materials: phonons limit electrical conductivity, optical phonons strongly influence optical response, while acoustic phonons carry heat in insulators and semiconductors.
It has been shown theoretically, that while the frequency of confined polar optical phonons in zincblende nanocrystals is equal to that of the bulk crystal phonons, the confined polar optical phonons in wurtzite nanocrystals have a discrete spectrum of frequencies different from those of the bulk crystal.
ndl.ee.ucr.edu /phonon-eng.htm   (910 words)

 Thesis Title: Phonon Transport and Coupled Electron-Phonon Transport in Nanoelectronic and High-Efficiency ...   (Site not responding. Last check: 2007-10-13)
Phonon mean free path in silicon estimated on the basis of Eq.
Directions of phonon transport in two-dimensional planes as given by different combinations of the direction cosines and the corresponding differencing schemes used for the BTE solver.
The fundamental transport process across a metal-semiconductor interface and the idea of the newly proposed model is to extract the interface phonon reflectivity and phonon relaxation time () by fitting the experimental data of the pump-probe measurement rather than fitting the interface thermal resistance and the thermal conductivity of the substrate.
web.mit.edu /ronggui/www/ThesisFigures.html   (3310 words)

 CMS—A First Look at Plutonium's Phonons   (Site not responding. Last check: 2007-10-13)
Phonons are lattice vibrations produced by the movement of atoms in a solid.
Wong’s team focused on the delta fcc form of plutonium for phonon measurements because this form is stable at high temperatures and the highly symmetric fcc structure can be retained at room temperature by adding less than 2 atomic percent of an alloy metal such as gallium.
The phonon energy was then measured and mapped along the three principal directions as a function of the scattering angle, which determined the wave vector of phonon propagation.
www-cms.llnl.gov /s-t/pu-phonons.html   (1278 words)

 PHONON - About Phonon   (Site not responding. Last check: 2007-10-13)
Phonon now has 65 employees, a 15,000 sq ft plant, $10M sales, is profitable, and expects strong continued growth.
Phonon's products are custom designed SAW devices & subsystems, which are specialty microcircuits for high performance analog signal processing, including filters, delay lines, and correlators.
Phonon also is developing moderate volume niche products for the defense telecommunications market and has growing export business.
www.phonon.com /about.asp?lrt=1   (436 words)

 Theory of electron-phonon interaction in the quantum Hall regime
We carefully studied this resonance phenomenon and predicted Rabi-like oscillations of electron populations in the presence of non-equilibrium phonons [21].
The opening of many-body gaps at odd filling factors [29] and the prospect of phonon spectroscopy of quantum Hall ferromagnets at even filling factors [24] were both considered.
Whilst the mechanism of magnetoroton creation by absorption of a non-equilibrium phonon was well understood, the mechanism of magnetoroton dissociation into unbound quasiparticles remained a mystery.
newton.ex.ac.uk /research/qsystems/portnoi/qhall.html   (831 words)

 Discover Phonon: Phonon, Open Source Multimedia   (Site not responding. Last check: 2007-10-13)
Phonon wants to fill in the gap and provide a multimedia API for KDE developers while at the same time giving the users more choices.
If you're wondering where the name Phonon comes from: The project started with the name KDEMM, but that name was neither pronouncable nor did it convey the project's purpose any better than the current name does (have you ever looked up "mm" on wikipedia?).
Phonon is a name for quasiparticles in quantum mechanics that describe a quantized mode of vibration in a solid.
phonon.kde.org /cms/1020   (295 words)

 CMS—Plutonium Phonon Dispersions   (Site not responding. Last check: 2007-10-13)
Unfortunately, PDCs in plutonium and its alloys have defied experimental determination for the past 40 years due to the inability to grow the large single crystals (measuring a few cubic millimeters) that are necessary for inelastic neutron scattering (INS) measurements and the high thermal-neutron absorption cross section of plutonium.
The experimental data are shown with the results of the best-fit model of the phonon and elastic contributions.
To extract the phonon energies, the spectra were fitted by convolving the experimentally determined resolution profile with a model function consisting of a Lorentzian for the elastic contribution and a pair of Lorentzians, constrained by the thermal phonon population factor, for the inelastic part.
www-cms.llnl.gov /s-t/phonon_disp.html   (725 words)

 PHONON Software   (Site not responding. Last check: 2007-10-13)
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.
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.
wolf.ifj.edu.pl /phonon   (188 words)

 phonon - HighBeam Encyclopedia
In certain phenomena it becomes evident that this energy is divided into discrete bundles (see quantum theory); the energy bundles behave like particles in some respects and are termed phonons.
These effects are most apparent at low temperatures where only a few phonons are present.
For example, interactions between phonons and electrons are thought to be responsible for such phenomena as superconductivity.
www.encyclopedia.com /doc/1E1-phonon.html   (235 words)

 Phonon - /Vir/blog/
The word phonon is normally used in quantum mechanics for quasiparticles that describe a quantized mode of vibration in a solid.
It is very different in that Phonon is a Qt-style API that is designed after common development tasks while GStreamer is an API designer after greatest flexibility and providing all features possible.
Again: there is no dubling effort, GStreamer can be integrated using Phonon very easy, no one acts like 1999 (the opposite is the case: Phonon shows that the developers are much wiser now) and with Phonon there will be a clear and stable multimedia API for 3rd party software vendors.
vir.homelinux.org /blog/index.php?/archives/20-Phonon.html   (863 words)

 Phonon - /Vir/blog/ (via CobWeb/3.1 planetlab2.cs.umd.edu)   (Site not responding. Last check: 2007-10-13)
With the announcement of the Phonon website (and for many it also was an announcement of the whole project) I received a lot of reactions.
On Friday and Saturday I was able to participate in presenting KDE on LinuxTag in Wiesbaden and on Saturday morning Michael Repplinger from NMM and I held a one hour presentation on Phonon and NMM and demoed the audio/video playback capabilities of the Phonon-NMM backend.
In the Phonon branch of kdelibs is a fake backend implementation that mostly uses QTimer to model how a real backend would work.
vir.homelinux.org.cob-web.org:8888 /blog/index.php?/categories/2-Phonon   (1468 words)

 [No title]   (Site not responding. Last check: 2007-10-13)
From the megahertz vibrations of ultrasound to the near-terahertz vibrations associated with heat, the underlying elastic anisotropy of the crystal asserts itself.
Phonons are elementary vibrations that affect many properties of solids--thermal, electrical, and magnetic.
Phonon imaging techniques provide physical insights into such topics as phonon focusing, lattice dynamics, and ultrasound propagation.
www.physics.uiuc.edu /people/Wolfe/Phonon.html   (155 words)

 First Full Mapping of Phonons in Plutonium, Physics Research Highlights, University of Illinois at Urbana-Champaign
Measuring the phonon dispersion curves is critical to understanding Pu's material properties, such as force constants, sound velocities, elasticity, phase stability, and thermodynamics.
For years, scientists have been unable to measure phonon dispersion curves in Pu because they were unable to grow the large single crystals necessary for inelastic neutron scattering.
Such understanding is essential to science-based stockpile stewardship, the assurance of the safety and reliability of the nation's aging nuclear weapons in the absence of actual testing.
www.physics.uiuc.edu /Research/Highlights/Pu-phonon_mapping.htm   (324 words)

 jonobacon@home » Phonon   (Site not responding. Last check: 2007-10-13)
I think a easy-to-use wrapper around a lower-level multimedia framework has advantages, but then at least KDE should emphasize that one of the particular backends is the ‘blessed’ one to at least encourage the majority of apps to target the same one.
Phonon is designed to abstract the choice away from KDE and instead rest it on the distributors.
It was explained already a zillion times that Phonon is not meant for sophisticated audio programs, heck is not even meant for non-sophisticated audio programs, it is meant for the 80-90% of the programs that just need to play a sound or show a video.
www.jonobacon.org /viewcomments.php?id=687   (3439 words)

 Electron-Phonon Coupling
In the one-electron model, the creation and destruction of lattice-vibrational quanta (phonons) is a principal mechanism for driving transitions between quantum states as electrons relax or are thermally excited.
But in the new experiments, the connection between lattice vibrations and electrons is much more intimate, and it is necessary to think of the two entities forming a composite, many-body system with its own spectrum of energies.
Instead, these holes are longer-lived and carry a cloud of "virtual" phonons that effectively raise the mass of the hole.
www-als.lbl.gov /als/science/sci_archive/phonons2.html   (994 words)

 Pressure Dependence of Phonon Anomalies in Molybdenum — ESRF   (Site not responding. Last check: 2007-10-13)
A collaborative group of researchers from Lawrence Livermore National Laboratory and the ESRF have been able to pin down the high-pressure lattice dynamics of the transition metal molybdenum by mapping its phonon energies under extremely high pressure.
Much of the interest in the H-point phonon is derived from its anomalous increase in energy with increasing temperature.
Using theoretical codes developed to model molybdenum, the group showed that there is strong sensitivity of the H-point phonon on the electronic band structure.
www.esrf.eu /NewsAndEvents/Spotlight/spotlight36phonon   (633 words)

 Phonon   (Site not responding. Last check: 2007-10-13)
Every harmonic vibration can be decomposed in the elementary vibrations called phonons.
At higher temperatures, vibration of an object is stronger and the number of phonons larger.
As every phonon carries a quantum of vibrational energy, this means that the internal energy of the object is also larger.
nanoatlas.ifs.hr /phonon.html   (68 words)

These will be considered to be one-body processes because the phonon and impurity degrees of freedom are not explicitly included in the model, and thus (neglecting Fermi degeneracy) such processes lead to terms linear in the distribution function.
The collision operator for polar optical phonon scattering in the one-dimensional model is then obtained by inserting (14.164), for both phonon emission and absorption, into a discretized version of (14.158).
The initial report of this calculation (Frensley, 1988b) employed a scattering operator for the LO phonons which was one-half of the correct value, due to an algebraic error.
www.utdallas.edu /eecs/ee/frensley/technical/opensyst/node35.html   (951 words)

 LWN: Phonon: Multimedia in KDE 4 (KDE.News)
Phonon will provide a task oriented API for multimedia, making it easy for KDE applications to use media playback and capture functionality (and more) resulting in application developers being free to concentrate on the user interface aspects.
In other words, KDE 4 applications will talk to Phonon, which in turn will talk to Gstreamer/Xine/[insert media backend here] which in turn will talk either to ALSA/OSS or to a daemon like jack which then talks to ALSA/OSS.
Phonon since it should provide a simpler API that is more familiar for
lwn.net /Articles/181706   (953 words)

 Phonon - Wikipedia, the free encyclopedia
Other lattices include a linear chain, which is a very simple lattice which we will shortly use for modelling phonons.
The behaviour of thermal phonons is similar to the photon gas produced by an electromagnetic cavity, wherein photons may be emitted or absorbed by the cavity walls.
Both gases obey the Bose-Einstein statistics: in thermal equilibrium and within the harmonic regime, the average number of phonons (or photons) in a given state is
en.wikipedia.org /wiki/Phonon   (2206 words)

 Phonon: Multimedia in KDE 4   (Site not responding. Last check: 2007-10-13)
As there is still a lot of work that needs to be done until Phonon is released with KDE 4.0 it is a great chance to get involved now, for example doing a Google Summer of Code project.
Phonon is supported by basysKom GmbH, Motama GmbH, KDE-NL who are organising a KDE Multimedia meeting and most importantly the community for providing feedback and code.
I was wondering if it is also going to be possible to write a phonon program that gets frames from a source (mic or just a file) and then the possability to modify the data (for instance real time effects) and then send it back to phonon, like jack.
dot.kde.org /1146140474   (1646 words)

 Electron-phonon coupling: ab initio deformation potential   (Site not responding. Last check: 2007-10-13)
For the case of DTW a-Si there are no coordination defects, though there are a small number of strained structures which lead to a reasonable distribution of localized tail and gap states.
Note that (1) the electron-phonon coupling is larger for conduction tail states than valence tail states (the conduction tails are also more localized), 2) the acoustic phonons are evidently more important to the tail states than optical phonons.
This is also borne out by a dominant low frequency (eg acoustic) modulation of the tail electronic energies in the next section.
www.phy.ohiou.edu /~drabold/czech/node11.html   (906 words)

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