Reddit reviews Physics of Atoms and Molecules (2nd Edition)

This is probably the book you want. It has problems and solutions, worked examples and best of all you can download the pdf with some googling. It's nice an succinct, and provides a good choice of topics for an undergraduate course.

Alternatively, there's the bible, Bransden and Joachain. The downside is that it's quite lengthy, and you probably only really care about the first ~10 or so chapters, although that amounts to about 450 pages worth of material. Also, as far as I remember there was no discussion of 6j symbols, but that's not the end of the world.

> What happens if the crystal is not cubic? I assume the circular dichroism cancels in some way, but why?

Cubic crystals tend not to alleviate the degeneracy of the M_J quantum numbers (I'm just talking about atomic transitions here, not crystal states or molecular states). There are situations where imperfections cause symmetry breaking that leads to alleviation of degeneracy, but not in a perfect crystal. This only applies to insulators by the way. If you have a metallic crystal, free currents in the metal can cause circular dichroism.

> In what way do things get complicated, exactly?

You can have chiral molecules, but floating in solution their relative orientations are random. As a result circular dichroism is not measurable in the ensemble unless you can cause macroscopic alignment of the molecules (like in a chiral nematic liquid crystal).

Also, it's complicated because molecular wavefunctions are not as intuitive as atomic wavefunctions. It's tough to figure out whether a molecule will exhibit certain optical properties without doing molecular orbital calculations. Though, group theory can give you a reasonable intuition for many cases.

> Are there any handles I could use to understand things better?

This is a pretty complex topic that requires an understanding of quantum mechanics and group theory. I didn't fully understand all of this until the last year of my Ph.D. You should take some classes in condensed and soft matter, for starters.

There are some books I guess I could recommend:

• Bransden and Joachain
  
  
• Tinkham
  
  
• Bishop
  
• Powell
  
  
• Henderson and Imbusch (my favorite)
  
  As for what keywords to use in a literature seach. I couldn't tell you. There are quite a few situations that lead to circular dichroism which require different physics to understand. Without knowing exactly what domain you are working in and the details of what you are trying to do, I can only suggest you look for "circular dichroism" on google scholar.
  
  I posted a comment a while ago describing, in detail, my workflow for understanding a topic. Maybe it will help you figure out what you are trying to figure out.