Calculation of ground and excited state polarizabilities of unsubstituted and donor/acceptor polyenes: A comparison of the finite-field and sum-over-states methods

In this manuscript, a relatively simple and inexpensive INDO/SCI finite-fie ld (FF) method for calculating polarizabilities (alpha) is demonstrated to give good agreement with results obtained by both the INDO/MRD/SDCI sum-ove r-states routine and published results using the RPA method. The FF method is as effective as the other techniques in predicting both ground and excit ed state alpha's in all substituted and unsubstituted polyenes studied. We observe the correlation described by Marder and co-workers between bond-ord er-alternation (BOA) and dipolar properties, such as the change in alpha be tween the ground and excited states (Delta alpha). In addition, qualitative , but not quantitative, agreement is seen between the calculated Delta alph a's of polar polyenes and those measured by Stark-effect spectroscopy.