L18.1 Born-Oppenheimer approximation Hamiltonian and electronic states
PROFESSOR: We began our introduction to molecules last time and tried to get a picture of the scales that are involved. In these objects we spoke of a lattice of nuclei and clouds of electrons in which a molecule had some scale, A. Then we had electronic energies E, electronic. We had vibrational energies. This is from the nuclei. And we had rotational energies. And they were one bigger than the other and bigger than the last. In fact, the electronic energies were bigger than the vibrational energies of the nuclei and bigger than the rotational energies of the whole molecule when it rotates as a solid body. In fact, the ratio was like 1 to square root of little m over M, where little m represents electron mass, and capital M, the nuclear mass. And so this number could be 10 to the minus 2, and then you have m over M. So that's the proportions. So this is larger than the second one, like 1 is larger than that, and the ratio between these two is this. So that's what...