I am new to this forum. I realized that I was browsing the forums way too much and I said why not register and post some questions that have been lingering in my head:

Here is one:

In a periodic solid, we almost always neglect the time factor of the Schrodinger equation:

[tex]e^{-i Et/hbar}[/tex]

So I guess the implicit assumption here is that there's no energy exhcange with the environment (no phonons, etc...) so that the total energy of the electron remains the same?

But what about the potential landscape the electron sees? The potential due to lattice atoms is changing periodically.

So the potential energy [tex]U(x) [/tex] in the Schrodinger equation is changing.

How can we understand this then?