Eulerian rotation factors

In the above, g are the Eulerian rotation factors necessary to rotate the local coordinate system used to evaluate the overlap back to the molecular coordinate system, and /are factors that Jaffe and Del Bene set to ... 

This treatment of the motion as that of a harmonic oscillator perturbed bj the presence of several positions of minimum potential energy is quantitatively useful only when the splitting is small compared with the spacing of the groups of levels. Beyond this point, other approaches are desirable. For example, it may be possible to express the Eulerian angles from one set of coordinates in terms of those of another and nuth the aid of this relation the rotational parts of both ip a and ipa may be factored out of the combination, leaving... 

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