Phonons Definition and 74 Threads

Hello all What is the definition of Normal mode? And what is the difference between normal mode and phonon? Are they same? Thank you!

In looking at phonons, and their energy, I came across the Partition function. THis was needed to calculate the internal energy of the solid. But howcome the Partition function is used, and not the GRAND Partition function? The number of phonons is not conserved, I know that, but isn't N, the...

If Einstein's box (http://galileo.phys.virginia.edu/classes/252/mass_and_energy.html ) is full of phonons instead of photons, the momentum is Mv=E/c' and time is t=L/c' where c' is the velocity of a phonon. The result should now be E=mc'^2 rather than E=mc^2. E=mc^2 is tenable to photons...

As every condensed-matter physicist knows, a phonon is a quantum of sound (or more precisely, of oscillations in a condensed-matter material). Clearly, sound is a wave. But quantum theory teaches us that, in a certain sense, sound is also a particle. Here I want to understand how far the view of...

Hi all My book says: "The reason that phonons on a lattice do not carry momentum is that a phonon coordinate (except for wavevector K=0) involves relative coordinates of the atoms". I can't quite figure this statement out. I understand the words, but I cannot see why it is an...

Hi guys, I don't understand how one would exactly determine a dispersion relation of phonons experimentally. There are two equations, one for momentum and one for energy conservation: \vec{k} - \vec{k^{'}} = \vec{G} + \vec{K} \omega - \omega ^{'} = \omega(K) where...

When two phonons interact in a material that is being heated, where does their energy go? Are the electrons in neighbouring atoms promoted? Is radiation given off? What about at a crystal boundary? My guess is that the phonon would be reflected, so the energy would be radiated back off again.

Whats the difference between phonons and gauge bosons?

Do phonons transfer energy between molecules/electrons within a conductor? If so, how does it happen?

Hi everybody, In chapter 10 of Kittel's "Introduction to Solid State Physics" it is said that the zeros of the dielectric functions determine the frequency of the longitudinal modes of oscillation, \epsilon(\omega_L) = 0, Eq. (17). Am I missing something or this is actually an "unproved claim"...

I'm looking for some notes concerning the following areas: Vibration in solids, Phonons, Specific heat capacity of solids, Electron gaz in solids, Debye model, stuff like that, any help ?

Homework Statement http://en.wikipedia.org/wiki/Phonon Can someone explain how the movie above the caption is a justification of the statement in the caption?Homework Equations The Attempt at a Solution

In dispersion relation diagrams, where omega is plotted against k, omega is sometimes nonzero at k=0. How is this possible? I thought a wave had to have a nonzero wavenumber :confused:

I thought optical phonons only existed in crystals with two or more types of atoms in a unit cell. But I keep reading references of optical phonons in single atom crystals, like silicon. What's the deal here?

How should I think about the concept of phonons? As I understand it, it is a wave which propagates with a speed similar to sound and models the movement of atoms in crystals. However how many atoms per phonon? And isn't phonons meant to be analogous to photons which are single units hence one...

Homework Statement Explain why there is no optical phonon in the dispersion curve for the one-dimensional monatomic chain of atoms. The Attempt at a Solution I am completely confused. I know that optical phonons get their name because when an array of 2 atoms of different charge...

I'm making my way through 'The Trouble with Physics' and am getting my head around phonons. It sounds to me like - phonons are a sort of virtual particle that results from emergent properties of the underlying forces - (IMHO) photons-as-particles could be considered phonons resulting from the...

I'm looking for some physical intuition as to why sound waves are quantized. I know two mathematical procedures for deriving phonons in a lattice: 1) impose the canonical commutation relations on the system ad-hoc, and 2) apply the Schrodinger equation to the lattice. But neither of these...

Hi folks, I'm having lots of trouble wrapping my head around this. For a start, how can you have a vibration along a [0 0 0] vector? I mean, where does it point?? And how can it have a finite momentum or frquency? (Does it?) Help would be greatly appreciated, but, please, speak slowly...

after reading the FAQ on how phonons, or modes of vibrations, are responsible for the slowing down of photons in dense materials, i still have some unanswered questions: i visualise phonons as something like qualities of a field, because they coordinate the deviant behavior of individual...

OK, we had Hall-effect equivalent for photons. And now there is Hall effect for phonons! http://physicsweb.org/articles/news/9/10/5/1 Zz.

I have never encountered phonon before, so I am going to make a list of statements, and please be generous to point out any mistakes. Thank you. 1. There is no new physics behind the idea of phonons: it is just an alternative way of doing things. 2. When one says that there are, say, 5...

Yeah, what are phonons? Has to do with heat I think... quantized vibrations in a rigid crystal lattice?... where do I find a quantum physics to English translation on bable fish? :biggrin:

Is there any general information that I can get about these discrete acoustical particles? I know that they have the same wave-like properties as photons, but they also have quite a few differences (i.e. sound by itself diminishes over time and does not exist in places with lack of a medium...