Recent content by csmallw

Thanks, this ought to help.

Ah! My reference text misled me. It seems to be the case that Δn = 0 must hold even for the finite square well. Consider two bound states |1> and |2>, with distinct energies E1 and E2, and consider the matrix element, \langle 1 | H | 2\rangle. H can operate to either the left or the right...

I've been reading up a bit on semiconductor quantum wells, and came across a selection rule for an infinite quantum well that says that "Δn = n' - n = 0", where n' is the quantum well index of an excited electron state in the conduction band, and n is the index of the valence band state where...

Thanks to you both. These comments are helpful.

Is there an easy-to-articulate difference between a polaron and an electron exhibiting electron-phonon coupling? Until yesterday, I had been under the impression that the difference between the two phenomena was related to the strength of the coupling. However, I looked up "polaron" on...

I've mostly been looking at Ascroft & Mermin, pp. 225-229, but also Ziman (Principles of the Theory of Solids), pp. 184-186. There's a bit too much material to quote, but after closer inspection, I guess Ashcroft and Mermin make no statements about the sign of the energy of holes, though their...

I've been playing around with some ideas of electron-hole pairs in semiconductors lately, have realized that I'm confused about some basic conventions that maybe the physics forum community could help clear up. Let's imagine that we have a direct gap semiconductor initially at zero temperature...

Thanks! Both these responses were helpful.

Hi all, I'm working on a Green function chapter of my dissertation, am referencing the equation, G(k,\omega) = \int_{-\infty}^\infty \frac{A(k,\omega')d\omega'}{\omega - \omega' + i0^+}, and I am trying to figure out the best way to credit it. I have noticed that condensed matter texts...

Not exactly. The volume of the BZ divided by the volume of a k-state is equal to the total number of available k-states for a given band in the system, i.e., the number of slots in the band that are available for charge carriers (electrons) to inhabit. Thus, if the volume enclosed by the Fermi...

Great! I am declaring my original post to be entirely correct. Thanks for everyone’s comments. This statement that the diagram is incomplete is not right, as far as I can tell. It would only be accurate for the example with electrons and photons in a vacuum, and the reason is that the diagram...

Thanks, and yes, the typical electron-phonon interaction is exactly what I am trying to describe. I am interested to know if Feynman diagrams would be an appropriate way to describe the electron-phonon interaction in a "cartoon" fashion. If so, what do the lowest-order diagrams look like?

Can you elaborate on what you mean when you say that the Feynman diagram is incomplete? Nomenclature aside, what I am trying to ask is, in a metal or semiconductor, can one electron in a state at energy \omega spontaneously scatter into one electron at a lower energy state \omega-\Omega, plus...

In a metal, can one electron decay into one lower-energy electron plus one phonon? (i.e., can the attached Feynman diagram occur?) If we replace phonons by photons and consider the process in a vacuum, I guess this is prohibited because you can always boost to a frame where the incoming and...

Thanks. Funny you should mention writing your thesis...I'm getting ready to do that myself in a month or two, which is why I am interested in getting a better handle on these concepts ;)