On the basis of geometries optimized at the Austin model 1 level, we use the intermediate neglect of differential overlap method coupled with a single configuration interaction technique to calculate the optical absorption spectra of oligomers of poly(paraphenylene vinylene), PPV, and their dimethoxy-substituted derivatives. Our results are in good agreement with experimentally measured visible and UV absorption spectra for oligomers and polymers, and provide a detailed interpretation of the electronic transitions involved, distinguishing the roles of localized and delocalized π molecular orbitals. In addition to the lowest energy transition, from highest occupied to lowest unoccupied delocalized π orbitals (2.5 eV in PPV), we calculate further structure in the absorption at higher energies associated with the delocalized π orbitals. These match well the measured absorption features in PPV compounds, at 4.5 eV (tetramer), 4.1 eV (pentamer) and 3.8 eV (hexamer, polymer).
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry