6.10: Polyacetylene (average bond model)
- Page ID
- 52341
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The carbon backbone of polyacetylene consists of alternating single and double bonds. Thus, there are two possible configurations: single-double-single-double or double-single-double-single.
The simplest model assumes that every carbon atom in polyacetylene is identical. The carbon-carbon bonds are then an average of single and double, and the unit cell is a single carbon atom and its associated hydrogen atom. Under this model, to construct a polyacetylene chain, we should translate the primitive unit cell a distance \(a_{0}\). Thus the primitive lattice vector is \(\bf{\tilde{a_{1}}} = a_{0}\tilde{x}\), where we arbitrarily positioned the chain parallel to the x-axis.