Recent content by tjny699

OK, I guess my other question still stands--after applying S_{+} to a spin down state do we need to then apply S_{z} to measure the spin of the resulting state? If so, does this not lead to an extra factor of \hbar

Thanks, Bill. S_{+} is called the raising operator in a number of sources that I've taken a look at. Naming aside, is it correct to apply S_{z} after applying S_{+} as I did in the first post? Sorry to linger on this but I'm trying to understand how this works in detail. The spin down state...

So the correct definition is without \hbar? Is there a reason that Sakurai includes it then?

Hi Bill_K, Thanks for your response. Do you mean that S_{+} should be defined without the \hbar? I always see it defined as in the original post. Also, later on the raising operator is defined in terms of the S_{x} and S_{y}, which definitely have to have the \hbar. Or perhaps I...

Spin 1/2--Raising and Lowering operators question Hi, Quick question regarding raising and lowering operators. Sakurai (on pg 23 of Modern QM), gives the spin 1/2 raising and lowering operators S_{+}=\hbar \left|+\right\rangle \left\langle-\right| and S_{-}=\hbar \left|-\right\rangle...

As for motivation: I'm a biochemistry student about to start work on a more physics intensive project and I got some old course notes form my friends to learn from. There is some discussion of the Debye theory of specific heats in arbitrary dimensions and I just want to make sure that I...

Hi kanato, Thanks a lot for the reply. I was under the impression that one could take the energy derivative with respect to temperate but also hold other thermodynamic quantities constant--the pressure for example: C_P=(\frac{\partial E}{\partial T})_{P} Is there a thermodynamic...

Hi weejee, thanks a lot for your reply. i think you are correct: i assumed that the motion of the positive background can be neglected. I think I've figured out how to get the potential and electron charge distribution using one of the Maxwell Equations, something called the "Thomas-Fermi...

Hi, I have a question about statistical mechanics. How do you calculate the density of states for phonons and electrons in a d-dimensional system (at fixed chemical potential) and when the dispersion relation for the electrons is E(p)=A |p|^g and for the phonons is w=v|p| To get the...

Hello, Chemistry grad student here about to start a physics-y project...so trying to learn about condensed matter physics. I get how screening works when you add a single charge to a gas of electrons, but what happens in a metal when you have a whole lattice, ie, a background charge density...