Theory of uncoupling and formulæ for the stark effect in H 2

Kronig and Fujioka have developed a perturbation theory to account for “uncoupling phenomena” in He2 . These phenomena manifest themselves as a distortion of the usual form of rotational level spacing. In a physical model the effects are attributable mainly to the gyroscopic action in which the rotation of the molecule causes the electronic angular momentum to become uncoupled from the internuclear axis. By this action the component of the electronic angular momentum about this axis does not remain a constant of the motion. Since the work of Kronig and Fujioka was not concerned with the case of H2 , and since those authors did not discuss the nature and justification of the approximations tacitly employed, the present writer thought it of interest to discuss relevant points and to develop a method for obtaining higher approximations. In a separate communication to this journal Dr. P. M. Davidson is dealing with matters concerning more directly the numerical applications of the theory. 1.2The Mathematical Basis . Kronig and Van Vleck have shown how to express the wave equation for a diatomic molecule in a convenient way. Kronig’s expression is equivalent to the following equation, except that our equation includes terms and operator forms not considered by Kronig. The correct wave equation for a diatomic molecule may be written as: