Exact diagonalization of Hubbard models for the optical properties of single-wall carbon nanotubes
Exact diagonalization of Hubbard models for the optical properties of single-wall carbon nanotubes
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DOI：
10.1088/1367-2630/12/8/083009
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发表时间：
2010-08-05
影响因子：
3.3
通讯作者：
Meneghetti, Moreno
中科院分区：
文献类型：
--
作者：
Alfonsi, Jessica;Lanzani, Guglielmo;Meneghetti, Moreno
由于在基于Hubbard模型的精确对角化(ED)计算中无法考虑大量的位置，通常采用多体微扰理论或平均场方法计算单壁碳纳米管(SWNTs)的激子态。我们使用小晶体方法，并表明，对于纳米管的pi结构，ED计算是可能的。我们将这种方法应用于小直径单壁碳纳米管，结果表明，当Hubbard模型的关联参数U=4t时，第一亮态与第二激发态发生交叉，其中t是跳跃积分。在U/t的第一亮态以上的能量处发现了两个或三个强的双光子吸收(TPA)态
Excitonic states of single-walled carbon nanotubes (SWNTs) have usually been calculated using many-body perturbation theories or mean field approaches because a large number of sites cannot be considered within an exact diagonalization (ED) calculation based on the Hubbard model. We use a small crystal approach and show that, for the pi structure of nanotubes, an ED calculation is possible. We apply this approach to small-diameter SWNTs and the results show that a crossing of the first bright state with the second excited states occurs when U, the correlation parameter of the Hubbard model, equals 4t, where t is the hopping integral. Two or three strong two-photon absorption (TPA) states are found at energies above the first bright state for U/t