Local-Density Functional Calculation Of The 3-Dimensional Band-Structure Of Poly(Phenylene Vinylene) (Ppv) And Comparison With Photoemission Data

TitleLocal-Density Functional Calculation Of The 3-Dimensional Band-Structure Of Poly(Phenylene Vinylene) (Ppv) And Comparison With Photoemission Data
Publication TypeJournal Article
Year of Publication1993
AuthorsDacosta, P. G., Dandrea R. G., Conwell E. M., Fahlman M., Logdlund M., Stafstrom S., Salaneck W. R., Graham S. C., Friend R. H., Burn P. L., and Holmes A. B.
JournalSynthetic Metals
Volume57
Issue2-3
Pagination4320–4325
Date Publishedapr
AbstractWe have carried out a local-density-functional calculation of the three-dimensional (3D) band structure of the conducting polymer PPV in order to determine the effects of interchain coupling. The major effects are due to coupling of carbons with hydrogens on rings in adjacent chains. Among the effects of this coupling are: splitting by up to 0.4 eV at various points of the Brillouin Zone of the double degeneracy that would exist if the two chains in the unit cell were uncoupled; loss of electron-hole symmetry; the wave vector at the valence band edge not along the chain direction; a band gap smaller by 0.2 eV than that obtained from 1D calculations; and interchain coupling large enough to suggest that polarons are unstable in PPV. The calculated density of states is in reasonably good agreement with that found in photoemission.