Recent content by VortexLattice

Hi, thank you for the reply, I read the relevant part of that. But there's still something I don't really understand, what is the significance of that contact potential, even if you can measure it? Does it affect the two metals if they are part of a circuit?

Well, maybe that would work, but metals are fundamentally different from semiconductors... For example, if the top of the valence band is now 5eV above the bottom of the conduction band (so they overlap), would you say that the band gap is now 0, or maybe -5eV? I kind of suspect you can't...

Hi all, I'm trying to find resources for how to calculate and find what I should expect as the result of the interface between two metals with different work functions. http://en.wikipedia.org/wiki/Anderson's_rule"]Anderson's[/PLAIN] Rule tells us how to do this for two semiconductors and...

Hi, thank you very much for the reply! However, after a quick glance at this I don't see how to get the permittivity assuming you already know the band structure... I'm sorry if I'm misunderstanding this, but is this what you meant?

I know experimentally, the permittivity of a material is ##\vec D = \epsilon \vec E##, and you can also relate the Polarization to it. So it's basically a response of the material to an applied E field. But that seems like it would be a fairly complex thing to figure out theoretically. I...

Thank you, I think I'm starting to get it! But I'm still confused about a couple things. I'm still trying to get my head around the unit cell deal. My textbook (Ashcroft & Mermin) says (talking about the example a hexagonal close packed metal, which has a unit cell of 2 atoms): I'm trying to...

Hi everyone, I'm trying to fit the Tight Binding molecule for a more complicated system, so I'm first trying to understand it for a simpler one, graphene. I've read several guides but they're all confusing me. Right now, I'm trying to understand the graphene example on this site. My biggest...

Well, I found a paper that does literally exactly what he wanted me to do. It even includes a spin-orbit interaction term, like he requested. The paper maps a TB model to some experimental results of the band structure. So that's good, but having read it, there was no way in hell I could've...

Hi all, A professor asked me to do something, but I'm not quite sure what he means -- He asked me to use Density Functional Theory (DFT) calculations of the band structure of a certain crystalline metal and adjust the matrix elements of a Tight Binding (TB) model to make a "minimal" TB model...

Hmmm, but that changes the final result! The final result they reach for this is separating ##\Phi_n## and ##\Psi_{e,n}## by separating this equation: ##(T_i + V_{ii} + E_{core})\Psi + \sum\limits_n \Phi_n (T_e + V_{ee} + V_{ei})\Psi_{e,n}(r,R) = E\Psi## and after doing many manipulations...

Hmmm, this doesn't seem consistent though. If ##V_{ei} = \sum\limits_{i,j} V_{ei}(|r_j - R_i|)##, I see what you're saying about the order of the operator ##R_i## not mattering (that's what you're saying, right?), but then what about ##V_{ii}##? That also just has multiplicative factors of...

Hi, I'm reading about the Born-Oppenheimer approximation for a solid and they're doing the formalism of it. They say that we can basically consider the ions stationary with respect to the electrons because they move so little and so slowly in comparison to them. They say that ##R_i## are the...

Ok, this actually helped me visualize it a lot. Thanks a bunch!

Thank you, but this is still just a mathematical explanation. It's still just saying, the slope of ##E## increases as ##k## increases, so in this mathematical definition of the density of states, you find these relations. Sorry, I know it's nitpicky, but I'm trying to think of an intuitive...

It's pretty common to divide out by the volume, since you often use boundary conditions to impose a volume that doesn't actually exist.