The expectation value of an operator on a wavefunction is the same as the integral over all space of the probability density of the wavefunction, namely the square of the wavefunction.

The first order approximate perturbed energy of a perturbed system is equal to the integral of the square of the wavefunction multiplied by the perturbed Hamiltonian.

Wavefunctions should be normalized before figuring out Huckel energies.

A vibrational mode with a change in dipole moment is IR active, whereas if there is a change in the polarizability it is Ramen active.

A P-branch occurs in rotational-vibrational spectra when the J level drops by 1 on a vibrational transition. A Q-branch occurs if it doesn’t change, and R branch exists if it goes up by 1.

Sometimes you don’t get a Q branch. I’m not convinced I remember why.

The 3P state is about 15B above the ground state, who’s name I can’t remember. Maybe it’s Bob.

Mercury 2+ is good for stuff.