This is an old revision of this page, as edited by H2g2bob (talk | contribs) at 01:40, 12 November 2005 (→Is this an error?). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 01:40, 12 November 2005 by H2g2bob (talk | contribs) (→Is this an error?)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)Is this an error?
"There is no energy gap for phonons" (under Dispersion Relation) - but then what about Phononic Crystals which do have energy gaps? - h2g2bob 11/11/05
- I suspect you'll find they're photonic crystals... -- CYD
- There are both, though phononic and photonic crystals are very similar (phononic crystals have gaps in the acoustic (long wavelength) dispersion curve I believe) - h2g2bob 12/11/05
Please elaborate
I have read this article a few times and still only have a vague concept of phonons. Can we get some more detail (and layman's explanations) on these sections:
"According to a well-known result in classical mechanics, any vibration of a lattice can be decomposed into a superposition of normal modes of vibration."
Can we link to an article about this rule, or give a short explanation if none exist?
"Secondly, we treat the potentials V as harmonic potentials, which is permissible as long as the atoms remain close to their equilibrium positions. (Formally, this is done by Taylor expanding V about its equilibrium value.)"
The link to screened in the sentence above this one helps explain it, but the link to harmonic oscillator doesn't really explain to me what a "harmonic potential" is.
"As we shall see in the following sections, any wavelength shorter than this can be mapped onto a wavelength longer than a."
This seems similar to aliasing in discrete-time sampled signal processing. If the analogy is close enough, should it be mentioned? Also, analogies to vibrations in strings would help me in particular, but I don't know how close these analogies are, and if they would give the wrong idea.
I guess the rest I don't understand simply because I don't know quantum mechanics... - Omegatron 14:26, Jul 21, 2004 (UTC)