Dear VIPEr friends,

I am teaching an advanced undergraduate group theory, molecular orbital theory, computational chemistry course this semester and having a ball. My question has to do with what we expect students to learn (what will they know and be able to do) when doing computational chemistry. I'm looking for answers beyond the obvious: learning the mechanics of setting up and visualizing the results of a calculation.

OK, so we all love the homonuclear diatomics, and how the 2p sigma is *below* the 2p pi for O2 and F2, almost equal at N2, and above 2p pi for C2, B2, etc.

 CO looks a lot like N2, but it's asymmetric...the 2p sigma is the HOMO. Disturbingly, the gap seems to be *larger* than in N2...why is that?!? Being isoelectronic, it seems like it should be about the same, but there should be *more* contribution from the oxygen orbitals in the *bonding* orbitals since O is more electronegative than C.