# Tag Info

### Solid-on-solid models

First, I'd say that the case you describe corresponds to a wetting transition, rather than to a roughening transition: the system goes from a regime of complete wetting (the wall if fully covered by a ...
• 10.5k

### Other than approximating the total energy of the system, what other information does the Hartree-Fock method provide?

In addition to energy, Hartree-Fock gives you the optimal wave function of the many-electron system (within the limits of the theory) as well. Any physical observable can be obtained from the wave ...

### Why don't positively charged metal ions (in a wire) move but electrons do?

The question is why the ions are localised and form a lattice, unlike the electrons. The reason is that they are typically 10000-100000 times heavier than electrons. Therefore they have very small, ...
• 25.3k
Accepted

### Using particle-hole symmetry of the Hubbard model to study the model at different densities

$\newcommand{\dag}{\dagger}$I realized it's because there are two spins that must be accounted for. Under the particle-hole transformation, we have \begin{align*} N = \sum_{i, \sigma} a^\dag_{i, \...
Accepted

### Why don't positively charged metal ions (in a wire) move but electrons do?

To answer this question, it is necessary to understand the structure of the metal at the atomic scale. A very simple way to see it is that the positively charged nuclei sit at fixed points in a ...
• 1,894

### Why don't positively charged metal ions (in a wire) move but electrons do?

It’s because the ions aren’t delocalized like the electrons are.
• 29
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### Finding the classical antiferromagnetic ground state for the Kagomé lattice

The full exercise is: Employing only symmetry considerations, identify a possible classical ground state of the triangular lattice Heisenberg antiferromagnet. (Hint: construct the classical ground ...
• 960
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### $p+ip$ pairing in a spinless fermion system with attractive interaction

A spinless fermion system with attractive interactions supports p+ip pairing. In a spinless fermion system, there is no spin degree of freedom, which means the pairing must occur purely in the ...
• 187
1 vote
Accepted

### Bloch oscillations and umklapp scattering induced by applied electric field

An Umklapp process is any scattering event where the ingoing and outgoing momenta differ by a (nonzero) reciprocal lattice vector. This includes phonon-phonon, but also electron-phonon and electron-...
• 960
1 vote

### What does a mechanical Josephson Effect look like?

The analogy is interesting but inexact, in a way that leads to significant differences. Entropy Rigid bodies can't spin forever in the universe. Even if you rotate an object in space, things will ...
• 3,626
1 vote
Accepted

### Local Maxima in a Dispersion Curve

So it turns out I found this issue, when using the built in plot function of Lamb-Wave-Dispersion it had a few datapoints there causing the entire plot to turn around. Extracting the data into excel ...
• 145

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