| Abstract
| - A sum-over-states approach has been applied to the calculation of the specific rotations of several substitutedoxiranes, 2-chloropropionitrile, and 30°-rotated ethane. In each case, the first few excited states proved tohave only a relatively small effect on the calculated specific rotation. It was necessary to use a very largenumber of excited states in order to achieve convergence with the results of the more direct linear responsemethod. However, the latter does not give information on which excited states are important in determiningthe specific rotation. Norbornenone is unique in that its greatly enhanced specific rotation as compared tonorbornanone is associated with the low-energy n−π* transition. The CC bond orbitals interact with theCO in the LUMO, and a density difference plot for going from the ground state to the first excited stateclearly shows the perturbation of the CC.
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