Electronic Correlation Effects in Cyclic Polyenes and in Polyacetylene
Most papers written nowadays on polyacetylene [1,2] seem to accept as a well-established fact that the origin of the optical gap in trans-(CH)x is due to bond alternation arising from the Peierls instability. Yet a completely different explanation for the origin of the optical gap has been given by OVCHINNIKOV and coworkers , who suggested that the gap results from electronic correlations and not from bond alternation. Estimating the relevant physical parameters for polyacetylene from substances such as ethane, benzene, ethylene and graphite , they concluded that the electron-phonon coupling is much too small to produce a bond alternation large enough to explain the measured gap.
KeywordsCorrelation Energy Electronic Correlation Effect Bond Alternation Stretch Force Constant Hubbard Interaction
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