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Parity law of the singlet-triplet gap in graphitic ribbons

Mohamad Al Hajj·Fabien Alet·Sylvain Capponi·Marie Bernadette Lepetit·Jean-Paul Malrieu·Synge Todo
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Abstract

This work explores the possibility to transfer the parity law of the singlet-triplet gap established for square ladders (gapped for even number of legs, gapless for odd number of legs) to fused polyacenic 1-D systems, i.e., graphite ribbons. Qualitative arguments are presented in favor of a gapped character when the number $n\_ω$ of benzene rings along the ribbon width is odd. A series of numerical calculations (quantitative mapping on spin 1/2 chains, renormalized excitonic treatments and Quantum Monte Carlo) confirm the parity law and the gapless character of the ribbon for even $n\_ω$.

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Mohamad Al Hajj, Fabien Alet, Sylvain Capponi, Marie Bernadette Lepetit, Jean-Paul Malrieu, Synge Todo. 2006-08-24. Parity law of the singlet-triplet gap in graphitic ribbons. https://doi.org/10.1140/epjb%2Fe2006-00259-9

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