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What is practical importance of Kohn anomaly for experimentalists and/or theorists?

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closed as not a real question by mbq Nov 20 '12 at 13:01

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Please specify the question. otherwise wiki – IljaBek Aug 16 '11 at 6:03
Sorry, I can't see what's wrong with this? It's very specific and I believe person with experience should describe it in a few words. Besides, I can't find answer on wiki, nor elsewhere. If someone could point out where on wiki answer is, i would be grateful and apologize for recklessness. – multipole Aug 16 '11 at 14:38
"practical importance" is always debatable. I would not know where to start. Did you try to google Kohn effect OR anomaly +application? there is no theoretical explanation/basis for the effect as far as I could understand from here (downvote itn't mine) – IljaBek Aug 16 '11 at 15:06
Downvote is mine -- this question is too vague. If you understand at least something about Kohn anomaly, then ask a precise question. If you don't then first go learn about it somewhere or ask a question that makes it obvious that you don't know what it is. – Marek Aug 16 '11 at 15:31

The practical importance of a Kohn anomaly is that it is a direct evidence of electron phonon coupling in a metallic system. This is used as evidence for electron-phonon coupling in BCS superconductors for example. Further, a Kohn anomaly is a sharp change in a lattice vibration that can cause a lattice instabilities, which can result in structural phase transitions of a material in extreme cases.

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