Homework Statement
I am asked to discuss the band structure of diamond. I saw the band structure of diamond has 4 filled valence bands and then 4 conduction bands. Silicon, the same.
Homework Equations
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The Attempt at a Solution
I'm feeling really silly because I don't understand why it is...
Hi all.
Suppose I have the ideal gas law $$P=\frac{RT}{v}$$If I'm asked about the partial derivative of P with respect to molar energy ##u##, I may think "derivative of P keeping other quantities (whatever those are) constant", so from the formula above I get $$\frac{\partial P}{\partial...
Say we have a Lagrange function with one multiplier a times a constrain. I minimize and solve the system to find a. I now add another constrain to the same system multiplied by the constant b. Is the value of a the same or can it change?
I don't understand why materials with low surface energy are hydrophobic and viceversa. All I can find are quick phenomenological explanations that don't quite deal with the physical (microscopic) process going on.
Could anyone provide a good microscopic picture of why it is that way? What's...
What the title says. Acting on a fermionic state with the number operator to a power is like acting with the fermionic operator itself. Does this allow us to define ## \hat{n}^k=\hat{n} ##? Or is there any picky mathematical reason not to do so?
Since there are no bonds at the other side of the surface, external layers of solids are usually closer to the next layer. This process is called relaxation. (Example in picture a here).
However, at a lecture I attended the other day it was mentioned that some surfaces present expansion...
If I have a Hamiltonian diagonal by blocks (H1 0; 0 H2), where H1 and H2 are square matrices, is the density matrix also diagonal by blocks in the same way?
Hi. I'm taking a look at some lectures by Charles Kane, and he uses this simple model of polyacetylene (1D chain of atoms with alternating bonds which give alternating hopping amplitudes) [view attached image].
There are two types of polyacetylene topologically inequivalent. They both give the...
Hi there. Excuse that I write it all in standard text but I don't know how to write it otherwise. I'll get right to the question and try to see if I understand the theory from the answer.
Suppose we have a system of two electrons, one spin up and one spin down in a system with 3 possible...
Hi.
I'll be doing a master's degree in nanophysics and working on electron transport in arrays of qubits.
I don't know anything (or barely) about the second quantization and would like a book which covers it, and on condensed matter overall.
So far I've been told about Bruus&Flensberg's...
Hi. This question most probably shows my lack of understanding on the topic: why are scalar fields Lorentz invariant?
Imagine a field T(x) [x is a vector; I just don't know how to write it, sorry] that tells us the temperature in each point of a room. We make a rotation in the room and now...
Hi. First, excuse my English.
In my lecture notes on classical electrodynamics, we are introduced to the Lorentz transformations: a system S' moves relative to a system S with positive veloticy v in the x axis (meassured in S), spacial axis are parallel, origin of times t and t' coincide...
Hi. I'm trying to understand tensors and I've come across this problem:
"Show that, in general, a (2, 0) tensor can't be written as a tensor product of two vectors".
Well, prior to that sentence, I would have thought it could... Why not?
Hi,
Etherington't reciprocity theorem states that distances measured by angular separation and by luminosity differ. My question is which one (if any of them) is the actual distance. I can understand they might differ in an expanding universe, but there's still a physical distance in such one...
Hi,
On the context of Maxwell's Demon, it's accepted that Landauer's principle (the erasure of a bit of information requires kTln2 of work) gives a solution to the paradox. The erasure of a bit of information can be seen as the modulation of a double well potential, as in the right side of the...
Hi. I hope this is the right forum for the question.
Landauer's principle says that the erasure of one bit of information (1 or 0) requires kBTln2 of heat production. When he talks about erasure, it means "resetting back to 0 (or 1)" after measuring. He says something along "this is needed as...
Hi
I'm finishing undergrad school at a university in Spain. It's taken me 5 years (was supposed to be 4) and my grades are mediocre (trying to reach a 7 out of 10).
My university itself is a trainwreck, a disaster. Most of what I've actually, properly learnt was during my year at Nottingham...
Hi
I'm having some trouble understanding Shannon entropy and its relation to "computer" bits (zeros and ones). Shannon entropy of a random variable is (assume b=2 so that we work in bits)
and everywhere I've read says it is "the number of bits on the average required to describe the random...
Electrons pile up inside a metal up to a maximum value in k-space (meaning the have velocity) and occupying all levels at 0K, solving the Schroedinger equation as running waves. So electrons moving => radiation being emitted. But electrons can't move to a lower energy state, so that would mean...