Skip to main content

New answers tagged

0 votes

Do Bloch waves from different bands have different energies and wave functions?

First, a brief review of Bloch's theorem, in my preferred style. Consider a particle in a periodic 1D potential, and let $T$ be the discrete lattice translation operator, $$\big(T\psi\big)(x) = \psi(...
J. Murray's user avatar
  • 69.9k
-1 votes

To what extent is the Laughlin wave function the essence of the FQHE?

It has been recently shown (https://www.mdpi.com/2079-4991/14/3/297) that the Laughlin wave function has nothing to do with the realistic ground state.
user92593's user avatar
2 votes

How to call ellipse packing structures?

I'm not aware of any specific terminology, but it makes sense to me to consider both of these as hexagonal configurations of hard-core ellipses. Reversing your compression operation, they can be ...
Anyon's user avatar
  • 2,664
1 vote

Why does the Fermi-level decrease with temperature increase?

The decrease in Fermi level with temperature is a consequence of charge conservation. The net charge per unit volume in the material is $n_d$, the concentration of donor electrons. At $T = 0$, the ...
zkrebs's user avatar
  • 11
1 vote
Accepted

Question about electrons in tight binding model?

In conclusion, in the tight-binding model we consider only one electron per atom. We do the assumption that there is ample room in each atom's orbitals, allowing us to postulate that the Pauli ...
Lucas's user avatar
  • 79
1 vote

How do you determine the basis of a crystal structure?

This is homework-like. However, I can help. If there is any atom purely inside the cell, you count it fully. If there is any atom on a face of the cell, you count it half. You have 8 corners of this ...
naturallyInconsistent's user avatar
5 votes

Why can you hammer a hole into an underwater ceramic cup?

Not an answer, but I did the experiment and it works (mostly) and you can't put photos in comments. The nail drove a neat looking hole in the cup. Turning the cup over revealed that the interior had ...
g s's user avatar
  • 13.8k
0 votes
Accepted

Intrinsic band gap vs work function of doped semiconductors

As you said, in a heavily n-doped semiconductor, the Fermi level $E_F$ is close to or a little above the conduction band edge $E_C$, but not very much. Conversely, in a heavily p-doped semiconductor, ...
freecharly's user avatar
  • 16.8k
0 votes

Where is the orthogonality center of the AKLT ground state matrix product state?

First, if I am correct, the matrix elements $\sqrt{3/2}$ should be instead $\sqrt{2/3}$. Then you can check that both left and right normalization conditions are satisfied on every site, i.e., $\sum_{\...
Rintarou's user avatar
0 votes

'Polarization' of waves in crystal lattice

An addition: There can actually be more than three modes of waves in a crystal lattice. If the primitive unit cell has more than one atom then there are so called "optical" modes. (Although ...
Sebastian Riese's user avatar
2 votes

'Polarization' of waves in crystal lattice

In air you have only one type, consisting of alternating compressions and rarefactions of the air. The movement of the air molecules are in that case back and forth in the direction of the wave ...
Jos Bergervoet's user avatar
-1 votes

Why does the magnetic field penetrate inside the superconductor?

It is because the density of superconductive pairs is finite. Therefor it takes a layer of finite thickness to block the external field.
my2cts's user avatar
  • 24.5k
0 votes

Why does the magnetic field penetrate inside the superconductor?

I think this is simply because of the impurities in the structure of the superconductor. I have read before that extra-purified superconductors actually perform worse in some situations, like how ...
Mehmet Umut Ata's user avatar
4 votes

Why the resistance in superconductors is zero?

DC Resistance in ordinary conductors is caused by the conduction electrons colliding with the conductor's ions and various other imperfections in the conductor.You're asking why superconductors are ...
Nadav Har'El's user avatar
  • 2,832
1 vote

Why do dental drills need such high rpm?

I think the answer is alot simpler than what's described in most of the answers. Teeth are brittle and you don't want to crack them so the less material you remove at a time the better. At a small ...
Peter Gerdes's user avatar

Top 50 recent answers are included