I went to the I-SEE event the other night and managed to hang in through a whole evening of Density Functional Theory. Here's a beginners' guide. I thought I might struggle when the speaker, Aron Walsh, began by saying that he'd be talking at the boundaries of chemistry and physics. I knew that I was going to struggle when he got onto Hamiltonian mechanics after about 5 minutes. That said, I did learn something and the whole thing was very engaging. The best advice Walsh had to offer was to say, "Make sure you choose the right Hamiltonian" which is something that I intend to take to heart.
Walsh had a nice line in self-deprecating humour. His response to a well-judged introduction by the Chair, where his impressive CV was to the fore, was to note that some people think that he is more impressive on paper than in person. It's not true though.