A SEMIEMPIRICAL STUDY OF HETEROCYCLE OLIGOMERS AND POLYMERS IN DIFFERENT DIELECTRIC MEDIA

Four common five-membered heterocycles-pyrrole, phosphole, thiophene, and furan- and their oligomers with the chain length of 2, 4, 6, and 1 0 units have been studied quantum chemically using the semiempirical P M3 parameterization. The oligomers of pyrrole and phosphole with the h omolytically dissociated N-H bond and P-H bond, respectively, and olig omers of thiophene and furan with one electron removed per monomer uni t (4n + 2 pi-electron bipolaron systems) have also been studied. The e lectronic properties of the respective polymers were extrapolated from the oligomer data. Bulk polymer effects on the electronic structure w ere modeled using the self-consistent reaction field theory in the mul ticavity approximation (MCa SCRF). (c) 1995 John Wiley and Sons, Inc.