Electronic Structure of Large Molecules: CNDO/S3 Model

The preparation of novel polymeric systems with prescribed electronic transport, photogeneration, and triboelectric properties requires a detailed knowledge of the electronic structure of the large molecules which are commonly utilized as pendant groups or molecular dopants in such systems. To achieve a systematic design capability for these materials, a spectroscopic CNDO-level molecular orbital model, called CNDO/S3, has been developed to describe simultaneously the photoemission and optical absorption spectra of aromatic heterocycles containing hydrogen, carbon, nitrogen, oxygen, and fluorine species. This model is shown to predict these spectra for a wide variety of such molecules including the polyenes, polyacenes, paracyclophanes, TCNQ, porphins, phthalocyanines, and other fused-ring heterocycles based on pyrrole and furan.