The metal-insulator transition in dimerized Hückel chains.
The metal-insulator transition in dimerized Hückel chains.
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二聚休克尔链中的金属-绝缘体转变。
DOI：
10.1063/1.2987702
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
S. Evangelisti
中科院分区：
文献类型：
--
作者：
A. Monari;G. L. Bendazzoli;S. Evangelisti
在单电子Hück el哈密顿量描述的线性链的情况下，研究了金属-绝缘体的转变。在这些体系中，这种转变是链键长度二聚化的结果，这导致了跳跃积分的类似二聚化。链性质的三个指标被考虑：最高占据轨道-最低未占据分子轨道间隙、极化率和局域化张量。在偶数开链的情况下，大链的行为在很大程度上取决于跳跃积分的交替结构。如果链的末端原子与其相邻原子弱成键，哈密顿量的能谱显示出两个准简并的本征值，所有的指示物都将预测(虚假的)金属行为。结果表明，如果从哈密顿量中去掉相应的特征向量，交替链的正常绝缘行为就会恢复。
The metal-insulator transition is investigated in the case of linear chains described by a one-electron Hückel Hamiltonian. In these systems, the transition is a consequence of a dimerization of the chain bond length, which induces a similar dimerization of the hopping integral. Three indicators of the chain character are considered: The highest occupied molecular orbital-lowest unoccupied molecular orbital gap, the polarizability, and the localization tensor. In the case of even open chains, the behavior of the large chains depends in a crucial way on the alternating structure of the hopping integrals. If the ending atoms of the chain are weakly bonded to their neighbors, the energy spectrum of the Hamiltonian shows two quasidegenerated eigenvalues, and all the indicators would predict a (spurious) metallic behavior. It is shown that if the corresponding eigenvectors are removed from the Hamiltonian, the ordinary insulating behavior of alternating chains is recovered.