Add useful examples of atomic physics

[lemmatum]

Add examples (probably some optimized functions plus visualizations in IPython notebooks) of physics useful for understanding atomic/spectroscopic effects.

Solutions for different modes of spherical harmonics of the Hydrogen atom is one idea that comes to mind. We could use SciPy's Cython API for special functions to generate these examples quickly.

Add any other useful concepts that could be computed or visualized here.

[lemmatum]

• [ ] Spherical harmonic solutions for Hydrogen atom as detailed in Ch 2 of Pradhan's Atomic Astrophysics and Spectroscopy
• [ ] Visualization of how different atomic state properties (i.e. orbital and spin angular momenta) affect the spherical harmonic solutions for an atom
• [ ] Demonstration of relativistic effects for atoms Z > 18 (Argon)
• [ ] Multi-electron system solutions (probably using approximations like central field approximation, Hartree-Fock method, and pseudo-potentials)
• [ ] Simple demonstration of Stark shift for energy levels of an atom under the influence of an external electric field

[lemmatum]

Probability of finding electron at a position for a certain orbital created using yt (because pretty!)

Hydrogen, n=2, l=1, m=1

Hydrogen, n=4, l=3, m=0