- #1
kof9595995
- 679
- 2
I think I did understand this once but now I am confused. If we choose the center-of-mass frame for a diatomic molecule, it also obeys the force law F=-kr, where r=(x,y,z), so why isn't it a 3-d harmonic oscillator, like an atom in solid? I know it may have something to do with the fact that gas molecules are free to rotate, but still I can't see the essential difference.