The Rotational Energy of Polyatomic Molecules

Abstract

It is shown that the quantized energy of a polyatomic molecule is approximately separable into the internal electronic and vibrational energy plus the rotational energy with the latter determined by solving the conventional problem of the rigid asymmetrical top. Because of the large oscillating terms in the Hamiltonian function due to interaction between vibration and rotation, this conclusion is not as obvious as it sounds, and seemed, if anything, to be contradicted by Eckart's recent investigation on the choice of a reference frame. The discrepancy, however, disappears when a second order perturbation calculation is made with Eckart's coordinates.