The total position-spread tensor: spin partition.
The total position-spread tensor: spin partition.
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DOI：
10.1063/1.4913734
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发表时间：
2015-03
期刊：
影响因子：
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通讯作者：
M. El Khatib;Oriana Brea;E. Fertitta;G. L. Bendazzoli;S. Evangelisti;T. Leininger
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文献类型：
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作者：
M. El Khatib;Oriana Brea;E. Fertitta;G. L. Bendazzoli;S. Evangelisti;T. Leininger
总位置扩散张量是位置算符的二阶矩累积量，是描述分子或扩展系统中电子迁移率的关键量。在目前的调查中，分区的TPS张量根据自旋变量的推导和讨论。结果表明，虽然自旋总和TPS提供的信息，电荷迁移率，自旋分区TPS张量成为一个强大的工具，提供有关自旋波动的信息。氢分子的情况下处理，无论是解析，通过使用1s Slater型轨道，和数值，在全组态相互作用（FCI）水平与V6Z基组。研究发现，对于很大的核间距，在一些低电子态中，分块张量随核间距的平方增长。这个事实与波函数中纠缠的存在有关。在FCI水平上研究了由Hubbard哈密顿量模型描述的非二聚开链和由等间距原子组成的线性氢链Hn（n ≥ 2）。氢系统显示出显着的最大值的自旋总和TPS（对应于高电荷迁移率）时，核间距离约为2玻尔的存在。这一事实可能与该区域发生的莫特转变有关。另一方面，自旋分区的TPS张量在长距离处具有二次增长，这一事实对应于磁系统中的高自旋迁移率。
The Total Position Spread (TPS) tensor, defined as the second moment cumulant of the position operator, is a key quantity to describe the mobility of electrons in a molecule or an extended system. In the present investigation, the partition of the TPS tensor according to spin variables is derived and discussed. It is shown that, while the spin-summed TPS gives information on charge mobility, the spin-partitioned TPS tensor becomes a powerful tool that provides information about spin fluctuations. The case of the hydrogen molecule is treated, both analytically, by using a 1s Slater-type orbital, and numerically, at Full Configuration Interaction (FCI) level with a V6Z basis set. It is found that, for very large inter-nuclear distances, the partitioned tensor growths quadratically with the distance in some of the low-lying electronic states. This fact is related to the presence of entanglement in the wave function. Non-dimerized open chains described by a model Hubbard Hamiltonian and linear hydrogen chains Hn (n ≥ 2), composed of equally spaced atoms, are also studied at FCI level. The hydrogen systems show the presence of marked maxima for the spin-summed TPS (corresponding to a high charge mobility) when the inter-nuclear distance is about 2 bohrs. This fact can be associated to the presence of a Mott transition occurring in this region. The spin-partitioned TPS tensor, on the other hand, has a quadratical growth at long distances, a fact that corresponds to the high spin mobility in a magnetic system.