Term: Peierls distortion
https://doi.org/10.1351/goldbook.PT07442

Definition:
Distortion of a regular one-dimensional structure with a partially occupied band to give bond alternation, eventually leading to dimerization or oligomerization. The degree of oligomerization, λ depends on the electronic population of the conduction band indicated by the wave vector of the Fermi level kF \[\lambda = 2\ \pi /k_{\mathrm{F}}\]

Note: A Peierls distortion opens a gap at the @F02341@, producing a net stabilization of the distorted structure. The Peierls distortion for chain compounds is analogous to the @J03361@ for molecules. The prototypical example of the Peierls distortion in organic chemistry is the bond alternation present in polyvinylene. PT07442.png

Related Terms:
1) fermi level (http://doi.org/10.1351/goldbook.F02341).
2) jahn–teller effect (http://doi.org/10.1351/goldbook.J03361).
3) dimerization (http://doi.org/10.1351/goldbook.D01744).
4) oligomerization (http://doi.org/10.1351/goldbook.O04285).
5) conduction band (http://doi.org/10.1351/goldbook.C01244).

Image: Polyvinylene (https://goldbook.iupac.org/img/inline/PT07442.png) 

Source: PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 381 (https://doi.org/10.1351/pac200779030293)

Citation: 'Peierls distortion' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.PT07442

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