Content request: Joerg's electronic structure course

[liamhuber]

i.e. 1D-TISE.

Nodes for making the potential (linspace and sin) already exist. Need to add functions to piece together to make the equation: direct diagonalization, laplace operator, finally pulling out the eigenvectors/values nicely (slicing them is already there). I think plotting is also already possible since we can chain together multiple matplotlib nodes to get pretty fancy stuff, but maybe some streamlining could be done there for the sake of students.

If 3D plotting works ok (plotly? Some flags in NGLView?) we could go all the way to 3D stuff.

It's low priority to add this, I just didn't want to totally lose track of the idea.