Excitonium

But user, this electron hole model is a thing only in condensed matter physics. I dont know if you can find it anywhere else.

To what an undergrad brainlet like me was taught, excitons are more like a state than real matter, thus you can not call it an element ?

> Metaparticles

What.

I think they call it quasiparticle.

I don't get how an electron can interact with a hole if a hole is the absence of said electron. It's like saying an electron can interact with itself.

The OP try to assume that a collection of excitons can be called excitonium , like each exciton is an atom of that.

Via coloumb interaction user. The model is more complex than only an electron and a hole, there are many thing more.

Yes, but how can it interact with empty "space"? Someone has told me that the electron-hole interaction is more complicated than an electron interacting via Coulomb's law with the ion that it left behind.

Well, it starts with jellium model, and it is hard to explain a bunch of quantum field stuff without math tho..

I've taken Quantum Mechanics I (first 5 chapters of Griffiths book). I struggle to understand how "holes" can move slower than electrons if one is just the absence of the other.

> Holes moves slower than electron

Maybe because their efficent mass is higher than electrons. But I still need the document which said that.

How much dirt is in a hole?

my balls

How can nothing be more massive than something?

I...don't know.

The weird part is after we've done calculated the efficent mass of electron, someone said let's calculate the mass of these holes. And turns out they are heavier than electrons.

Weird.

>At last, philosophy has been made real
You keep running your mouth like that and I'm going to find you.

t. philosophy major

>efficent mass

The term is effective mass. It arises from the fact that your electrons are not free particles, but have a periodic potential they interact with. As a result of this, your electrons will not move with an applied field as they would if they were free. The easiest way to account for this is to assign the electron an effective mass (which depends on band curvature and is not constant for different band states). This will let you continue treating your electrons as "free", just with a different mass, which makes calculations much simpler than considering the effect of the potential at each point.

Further, someone was referring to holes as meta-particles. The correct term here is quasiparticles. The basic idea is that it is easy to deal with an electron in an otherwise empty band (since you don't have to consider interactions with other electrons) and a full electron band (since all the states are filled). It wouldn't be very easy to look at a band that is almost full by considering all the electrons in it, since there are many.

Instead, we take the easy case of a full electron band and add a particle with the same charge as an electron, but positive, into the state we want to "remove" an electron from. Adding this positive-charged "hole" quasiparticle into the full electron band gives us the state where a single electron is missing. Then, in calculating what this electron absence will do, we can simply consider the motion of this positive quasiparticle instead of considering the N-1 electrons.

And, I should add, the holes and electrons are in different bands (of course, technically you have electrons in all the bands, but for the filled bands you only consider the motion of holes and for the almost empty bands you consider the motion of electrons). Since the effective mass depends on band curvature, the effective masses of holes and electrons are different.

This is your brain on Griffiths.
t. Someone who actually took intro QM (Shankar i presume)

What do you mean by "add a particle with the same charge as an electron but positive into the state" ? You add some extra variables into your model or what?

What you're saying smells like the typical band model people use to explain conductivity. But "excitonium" was supposed to be a discovery, how is it anything new?

Oh yeah, I was just explaining the most basic ideas of band structure. This is because it was clear there was a lot of confusion about that.

As for excitonium I won't comment because I don't really know shit about it. Excitons, which are bound pairs of electrons and holes, definitely have been observed before and are the basis of most LEDs, for example. Apparently this is some new phase of matter, maybe all/most of the conduction electrons are in excitons? Just a guess.

This gets a bit handwavy but can probably be done properly with creation/annihilation operators acting on the filled-band wavefunction. As I understand it, you literally just consider a filled valence band, and then in the state where you're missing an electron in the material you add a hole, thus giving you the same charge distribution.

Quantum science is a pseudo science

any idea on how to explain the band gap. The nearly free electron model with 2 atoms i get, and how different energies come to be i get aswell. But then it starts to extrapolate to N atoms, and it gets very fuzzy on how you get those N different energies. They don't show it explicitely and the 2 atom model wants those 2 atoms next to eachother, in the case of N atoms this can no longer be so. How to explain the band gap?
hijacking this thread senpai

So it's just a fudge variable. Good to know.
Next.

No, I wouldn't say that it is. I don't know what you even mean by that in this context. Quasiparticles extend far beyond holes, and are quite well described by theoretical physics. However, I am not a theoretical physicist so I just take their word for it. I'm sure you can find much more on this by looking up courses/books on theoretical quantum matter or similar.

Atomic/molecular orbitals overlap. Not every atom has to be close to every other atom. For example, if you have two different 2-atom systems that form hybrid orbitals and then bring them close to each other, the hybrid orbitals will overlap and hybridise further. Different bands arise from different atomic orbitals overlapping. Some regions in energy do not fall within any of the bands, hence band gaps.

Really, this stuff is at least a course in itself and well described by many introductory condensed matter courses.

I like how nobody knows what this great "discovery" is about
But the tabloids keep writing about it, the more confusing the more redit golds it gets

Thanks for explaining, it's not that I didn't get the basic gist of it, but
> For example, if you have two different 2-atom systems that form hybrid orbitals and then bring them close to each other, the hybrid orbitals will overlap and hybridise further.
this made me realise that if you take 2 2-atom systems, their energies are going to be degenerate, and then you'll get that hybridization. Really, sometimes it's just a basic thing you need to be remembered about to know what's going on again
thanks mate

T-thanks for fixing me.

No problem. It does annoy me that, as is so often the case when trying to explain something to someone else, I find that my own understanding has gaps where gaps shouldn't be. Maybe someone else can elaborate where I have waved my hands and told you to look elsewhere.

Actually I enjoy this to be honest. A chance to finding gaps means a deeper understanding about the subject.