An AM1 study of the two-photon absorption in bis(styryl)benzene derivatives

We present an AM1 semi-empirical study of the two-photon absorption (TPA) properties of a number of bis (styryl)benzene derivatives. In a recent report these systems were shown to be good two-photon absorbers. An analysis based on the INDO scheme was also included to calculate the TPA properties. The present study, based on configuration interaction consisting of single and double excitations, is compared with the above INDO model with respect to the prediction of energetics and TPA properties. The results indicate qualitative agreement, but serious questions regarding the applicability of both methods remain.