Rigid Rotor - Orthogonality

[@jiajunlei7783]

Hi Dr. Stuart, why there is a sin(theta) as integration factor?

[@PhysicalChemistry]

It's because the integral is performed in angular coordinates. Any time the integral is over the θ and ɸ coordinates, the integration factor will be sin θ dθ dɸ. (You may be more familiar with the integration factor r² sin θ dr dθ dɸ, but here we are only using the two angular coordinates.)

[@jiajunlei7783]

@@PhysicalChemistry Thanks for your reply. I really enjoyed your lectures, I never was able to connect from quantum mechanics to macroscopic properties until watching your lecture, the logic is so clear. THANK YOU!!

[@PhysicalChemistry]

@@jiajunlei7783 Thanks. I'm glad to have been of some help. It's easy to get lost in the details and think quantum mechanics is very abstract, without much practical application. But once you know how to make the connections, it explains MANY different things.