I apologize! I've reread you post, and found the text you were referring to, and now understand the notation and the context.
First I will explain my first post (so I am not too confusing), then I will answer your question as best I can:
In the copy of "Optical Orientation" on Google...
The reason why I want to see the text is because it sounds completely messed up!
Usually when you discuss double groups in the context of spin-orbit coupling, the operators in your group are whatever is in the single group (T), plus time reversal (R) - not the full rotation group (D). The...
There are two parts to your question:
First, one has to ask how the atoms arrange themselves with respect to one another at the microscopic level. This information is what people usually refer to as the "crystal structure". Usually, the arrangement of atoms is periodic - it repeats in a...
Your post would have been better places in the Solid State section of the forum.
There are a couple of layers to answer your questions.
If you ignore the fact that electrons repel each other by Coulomb repulsion, then the solution is simple. In this case, you write your solutions to the...
Trust me, there's no mess here (anymore) :P
Keep in mind, the debates I was referring to occurred in the 1930s. Since then we've sorted out a lot of things.
You have to keep in mind that neutron diffraction really only emerged in the late 1940s / early 1950s, and I think was the first...
I think the issue is that allow ferromagnets break symmetry, their broken symmetry state is still an eigenstate of the quantum Heisenberg Hamiltonian. The Neel state on the other hand is not an eigenstate of the Hamiltonian. There was a long debate about whether such a state was actually...
I've used daveyrocket's method with a Lorentzian of small width in the past. Not sure if this is the most efficient approximation for the delta function, but it's real easy to work with.
Well, if you don't believe it, calculate it yourself with the Heitler London wavefunctions!
This is done in Ashcroft + Mermin, if you want a reference.
The point is that the total many electron wavefunction must be antisymmetric with respect to interchange of the two electrons. If the two...
When you solve for the bloch states of an electron in a periodic potential, and periodic boundary conditions, you get states with momentum in particular directions. If you want a net current of electrons, you need a net momentum of electrons in the direction of the current. When you apply an...
Firstly, let's correct your terminology a little bit. The Heisenberg interaction is just:
\mathcal{H}=\mathcal{J}\sum_{i} S_i \cdot S_{i+\delta}
You have rewritten it in terms of S^z, S^+ and S^- operators which is fine.
Your next step is to write it with respect to bosonic operators a...
There are a few codes you can find online, I think python scripts. You can probably reverse engineer them. I think Kristjan Haule's website has a few downloads, and there is also some DMFT code with the ALPS project.
It really depends on what you consider to be "mastering" a particular field. In my opinion, modern physics is so far developed that true expertise in a field of physics takes many many years (like twenty plus), so I don't think it is possible to become a true expert in both theoretical and...
In my experience, lecturer positions at universities are very hard to get, unless you know people. Almost all hirings in these positions at my current university are internal, either a PhD/Postdoc already at the university, or the spouse of a professor. If you are in a country that is currently...