Chirality-Induced Spin Selectivity in a Coarse-Grained Tight-Binding Model for Helicene,The Journal of Physical Chemistry C

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Chirality-Induced Spin Selectivity in a Coarse-Grained Tight-Binding Model for Helicene
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2019-10-28 , DOI: 10.1021/acs.jpcc.9b07764
Matthias Geyer , Rafael Gutierrez , Vladimiro Mujica _{1,

2} , Gianaurelio Cuniberti

Affiliation

Spin-dependent effects in helical molecular systems, leading to the so-called chirality-induced spin selectivity (CISS) effect, have strongly attracted the attention of the chemical and physical community over the past few years. A large amount of experimental material has been collected so far, and different theoretical approaches have been presented to rationalize the CISS effect. The problem is, however, still a subject of debate. We present a semianalytical coarse-grained atomistic description of the electronic structure of a simple helical molecule, including spin–orbit interactions. For reference, we consider helicene, which is a pure carbon-based helical system with no chiral centers, and which has been previously shown experimentally to display a CISS effect. Our model exploits perturbation theory and a Löwdin-like partitioning to obtain an effective π–π Hamiltonian, where all coupling coefficients depend on the helical geometry and predefined Slater–Koster parameters. As a result, they can be explicitly computed, thus providing physically meaningful orders of magnitude. We further discuss the conditions under which a nonvanishing spin polarization can be obtained in the model. We expect that our approach will serve to bridge the gap between purely phenomenological model Hamiltonians and more advanced first-principles methodologies.

中文翻译：

手性诱导的自旋选择性在粗粒紧束缚模型中的螺旋烯。

在过去的几年中，螺旋分子系统中的自旋依赖性效应导致所谓的手性诱导的自旋选择性（CISS）效应，引起了化学和物理界的极大关注。迄今为止，已经收集了大量实验材料，并且已经提出了各种理论方法来使CISS效应合理化。但是，这个问题仍然是一个争论的话题。我们介绍了一个简单的螺旋分子的电子结构的半解析粗粒度原子描述，包括自旋-轨道相互作用。作为参考，我们考虑螺旋烯，它是一个没有手性中心的纯碳基螺旋体系，先前已通过实验证明具有CISS效应。我们的模型利用摄动理论和类似Löwdin的分区来获得有效的π-π哈密顿量，其中所有耦合系数均取决于螺旋几何形状和预定义的Slater-Koster参数。结果，可以显式地计算它们，从而提供物理上有意义的数量级。我们进一步讨论了在模型中可以获得不消失的自旋极化的条件。我们希望我们的方法将有助于弥合纯现象学模型哈密顿主义与更高级的第一原理方法论之间的差距。我们进一步讨论了在模型中可以获得不消失的自旋极化的条件。我们希望我们的方法将有助于弥合纯现象学模型哈密顿主义与更高级的第一原理方法论之间的差距。我们进一步讨论了在模型中可以获得不消失的自旋极化的条件。我们希望我们的方法将有助于弥合纯现象学模型哈密顿主义与更高级的第一原理方法论之间的差距。

更新日期：2019-10-28

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