Parity law of the singlet-triplet gap in graphitic ribbons
Parity law of the singlet-triplet gap in graphitic ribbons
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DOI：
10.1140/epjb/e2006-00259-9
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发表时间：
2006-01
期刊：
影响因子：
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通讯作者：
M. Al Hajj;F. Alet;S. Capponi;M. Lepetit;J. Malrieu;S. Todo
中科院分区：
文献类型：
--
作者：
M. Al Hajj;F. Alet;S. Capponi;M. Lepetit;J. Malrieu;S. Todo
这项工作探索了将方梯（偶数支腿有间隙，奇数支腿无间隙）建立的单重态-三重态间隙的宇称定律转移到熔融多聚1-D系统（即石墨带）的可能性。当沿带宽的苯环数ω为奇数时，提出了支持间隙特性的定性论证。一系列的数值计算（自旋1/2链的定量映射、重整激子处理和量子蒙特卡罗）证实了偶nω时带的奇偶性和无隙性。
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 nωof 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) confirms the parity law and the gapless character of the ribbon for even nω.