Binding energy of 1B{sub u} singlet excitons in the one-dimensional extended Hubbard-Peierls model
Binding energy of 1B{sub u} singlet excitons in the one-dimensional extended Hubbard-Peierls model
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DOI：
10.1103/physrevb.55.15368
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发表时间：
1997-06
影响因子：
3.7
通讯作者：
Z. Shuai;S. Pati;W. Su;J. Brédas;S. Ramasesha
中科院分区：
文献类型：
--
作者：
Z. Shuai;S. Pati;W. Su;J. Brédas;S. Ramasesha
利用对称化密度矩阵重整化群公式，我们研究了N=80的共轭链在扩展的Hubbard-Peierls模型（参数为U，V和{delta}）中最低光学允许激子（1B{sub u}）的电子结合能.三个对称性，C{sub 2}，自旋宇称，和电子空穴对称性，已被应用于构建投影算子。激子结合能和激子能量之间的比值的分析结果，揭示了目前的实验和理论上的争论激子结合聚乙炔和聚对苯亚乙烯。我们表明，在没有二聚化，激子的结合能是vanishingly小的U/t高达5和V/t高达2.3，对于一个有限的二聚化，只有当V是足够大的激子得到显着绑定。这一结果质疑了强相关图像对共轭聚合物的适用性，其中激子结合能等于V。{copyright} {ital 1997} {ital The American Physical Society}
Using a symmetrized density-matrix renormalization-group formulation, we have investigated the electronic binding energy of the lowest optically allowed exciton (1B{sub u}) within an extended Hubbard-Peierls model (with parameters U, V, and {delta}) for conjugated chains with N=80 sites. Three symmetries, the C{sub 2}, spin parity, and electron-hole symmetries, have been applied to construct the projector operator. Analysis of our results on the ratios between exciton binding energies and exciton energies, sheds light on the current experimental and theoretical controversy on exciton binding for polyacetylene and polyparaphenylene vinylene. We show that in the absence of dimerization, the exciton binding energy is vanishingly small for U/t up to 5 and V/t up to 2.3; for a finite dimerization, it is only when V is large enough that the exciton gets to be significantly bound. This result questions the applicability to conjugated polymers of the strong correlation picture, in which the exciton binding energy is equal to V. {copyright} {ital 1997} {ital The American Physical Society}