stunningllama

The online version can read arbitrary files, but the issue is the examples shown in the animations were made with the desktop version after I made changes to the file format, so they can't be loaded in the web version. Honestly the web version kinda sucks, but I'm keeping it up because it's really accessible and simple to use.

> Why it is not possible to add the examples? Is there any technical problem or just lack of time?

Do you mean a link to open the desktop app? I guess I could try, but I think it's easy enough to find the example manually. There's also some technical issues with it.

> I din't notice that the online version has less features.

I guess the line "The desktop version [2.0.1] is much faster and has many more features as well as additional examples" wasn't clear enough. I'll see about improving it.

> When it shows the current, all of them have the same length.

I think I'll add an option to make the arrow length vary. I'll also add a gamma slider.

1. I wouldn't be able to do that because these examples are only available in the desktop/steam version.

2. Again this is feature is in the desktop version only (check "View charge carriers"). You can reverse the voltage source by setting the voltage negative.

3. That's a nice suggestion, I think I'll implement it in the next release.

I have no plans to update the web version any further.

The electrons are repelled or attracted by the electric field, which is in turn determined by the average charge density. So two electrons in the animation don't directly repel each other, but the electrons do influence each other through the field.

Not too difficult. Stay tuned for the 3D version.

The simulation does calculations on the fields only, so it keeps track of the average electron and hole density at each point in space. There is, however, a one-to-one correspondence between the behavior of the fields and the motion of individual particles, which is what makes these animations possible. What I mean by this is the diffusion equation is satisfied by the probability density of a particle undergoing a random walk. So given an electron density that obeys the diffusion-drift equations we can make dots undergo a random walk with drift that turns out to match the given density function (the result is the second set of animations).

Oh, yes. I updated the page so the animations are now under the CC-BY license. Glad to hear you like them!

I recreated Veritasium's setup in my simulator and measured the current through the load resistor, the results of which are here: https://imgur.com/a/sxVihf0

The gap between the wires is about 1 micrometer, so light should take about 3 fs to propagate through. The simulation output approximately matches this prediction, and over the first few tens of femtoseconds the current increases, with a jump at around 70 fs due to the reflected wave. All of this is pretty much in line with the results of Veritasium's experiment.

Thanks for bringing it up. I might include this as another example in my sim.

On my info page (https://brandonli.net/semisim/info) there's a list of things my simulation can and can't do. After taking a look at the paper you mentioned, I think simulating it may very well be possible, however it might take a bit of effort. As for graphene, its band structure is different enough that I don't think it would work.

Note that my simulation is intended for educational purposes only, not scientific research.

- Brandon

That's exactly right! In my simulation quantities like E and J are vectors with x and y components. In contrast B can be thought of as a vector (or bivector, technically) pointing in the z direction, but since it it only has one component it's simpler to just lump it in with the other scalars. (Aside: Having the simulation be in 2D brings in some interesting toplogical restrictions on circuits).

- Brandon

Brandon here. I was very much inspired by Falstad's applets. I had him take a look at my simulation and he generously offered to make a JS port.