QuantumChemistry?: In a simple model, chemical spectra result from photon emission connecting energy eigenstates of isolated atomic or molecular Hamiltonians. (A full QuantumMechanical? treatment must include the operators for the E and M fields). The simplifying SeparabilityAnsatz pervades this study. The nuclear and electronic eigenstates possess symmetries inherited from their respective Hamiltonians. The symmetries of initial and final states determines whether they can be connected by an electric dipole event. The chemical applications of GroupTheory? thus form a useful tool for avoiding many difficult calculations in QuantumChemistry?.
Funny, the abbreviation for the course Group Theory, Quantum Chemistry, and Spectroscopy looks something like (I forget exactly--it's been almost a decade now) GRP THERY in the textbook store. It looks like you're buying materials for group therapy. --DavidLiao