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| == 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 | |||
| == Please elaborate == | == Please elaborate == | ||
Revision as of 16:12, 11 November 2005
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
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)