VIBRONIC TRANSITION MOMENTS
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Date
1981
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Publisher
Ohio State University
Abstract
The application of the Herzberg-Teller theory of vibronic transition moments is examined. The contribution of the Herzberg-Teller mechanism to the transition moment induced by a normal vibration Q, may be written. $$\bar{M}_{1j}= \left\langle \left(\frac{\partial \phi_{1}}{\partial Q} \right)_{Q_{0}} |Q\bar{r}|\quad\psi_{j}\right\rangle +\left\langle \phi_{1}\quad|\bar{r}Q|\left(\frac{\partial \psi_{1}}{\partial Q}\right)_{Q_{0}}\right\rangle.$$ The evaluation of this expression usually depends upon an expansion of the partial derivatives of the electronic parts of the wavefunctions in terms of the set of electronic wavefunctions based upon the equilibrium nuclear configuration. This set of wavefunctions is incomplete since it does not include the wavefunctions obtained from nuclear configurations displaced from equilibrium. We have shown by a simple example that this curtailment of the set of wavefunctions in the expansion can produce significant errors in the calculation of the transition matrix. A method to account for the contribution of the displaced wavefunctions in pi molecular orbital theory is presented, and the results applied to a simple example.
Description
This work supported by U. S. Public Health Services Grant $\#$21897-06, National Institute of General Medical Sciences.
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