Multiple self-localized electronic states in trans -polyacetylene

doi:10.1073/pnas.0601314103

Multiple self-localized electronic states in trans-polyacetylene

*Departments of Nuclear Science and Engineering and Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
^‡Department of Materials Science and Engineering, Ohio State University, Columbus, OH 43210

Edited by Esther M. Conwell, University of Rochester, Rochester, NY, and approved April 26, 2006 (received for review February 15, 2006)

Abstract

Electronic structure calculations on a conjugated polymer chain by Hartree–Fock and density functional theory show a sequence of self-localized states, which stand in contrast to the single self-localized soliton state described by the Su–Schrieffer–Heeger model Hamiltonian. An extended Hubbard model, which treats electron–electron interactions up to second neighbors, is constructed to demonstrate that the additional states arise from a strong band-bending effect due to the presence of localized electric fields of charged solitons. We suggest the optical response of these electronic states may be associated with the near-edge oscillations observed in photo-induced absorption spectra. Our calculations indicate further that in the presence of counterions, the additional localized states continue to exist. Implications regarding soliton mobility and high-resolution ion sensing are briefly discussed.

Footnotes

^§To whom correspondence should be addressed. E-mail: syip{at}mit.edu
Author contributions: X.L., J.L., and S.Y. designed research; X.L. performed research; X.L. and J.L. contributed new reagents/analytic tools; X.L., J.L., and C.J.F. analyzed data; and X.L., J.L., C.J.F., and S.Y. wrote the paper.
Conflict of interest statement: No conflicts declared.
This paper was submitted directly (Track II) to the PNAS office.
Abbreviations:

Abbreviations:

CH,

carbon–hydrogen;

DFT,

density functional theory;

DOS,

density of states;

HF,

Hartree–Fock;

SSH,

Su, Shrieffer, and Heeger;

t-PA,

trans-polyacetylene