Structure-property relationships for spin-orbit effects in chiral molecules

纳米自旋电子学在最小的规模上依靠自旋而不是电荷作为信息载体，有望在微型电路中实现信息存储、传输和处理的新设备。在过去的几年里，实验证明螺旋分子可以使电子电流自旋极化。虽然这种效应可以定性地从自旋-轨道耦合的角度来理解，但目前可用的理论只有在假设不切实际的大的有效自旋-轨道耦合参数的情况下，才能合理地解释令人惊讶的巨大的自旋极化幅度。基于量子力学第一原理的理论描述可以阐明这些差异，但仍然缺乏。本项目的目标是对手征诱导自旋滤波效应进行第一性原理描述。这将有助于阐明这种效应的大小背后的物理基础，并建立结构-性质关系。基于这些关系，应该为实验提出建议，这将允许进一步检验理论描述。此外，应开发从第一原理电子结构中提取有效的自旋-轨道耦合参数的方法，这允许与分析模型进行比较，并可作为粗粒度方法的基础，以模拟器件的构建块。除了这种方法的基本有趣的方面，这将允许先进的分子自旋电子学，有可能为这种设备提供负担得起的和可微调的材料。

Nanospintronics, which relies on spin rather than on charge as information carrier on the smallest scale, holds the promise of new devices for information storage, transport and processing in miniature circuits. In the past few years, it was established experimentally that helical molecules can spin-polarize an electron current. While this effect can be understood qualitatively in terms of spin-orbit coupling, theories available today can rationalize the surprisingly large magnitude of spin polarization only when assuming unrealistically large effective spin-orbit coupling parameters. A theoretical description based on the first principles of quantum mechanics can shed light on these discrepancies, but is still lacking. The goal of this project is a first-principles description of the chiral induced spin filtering effect. This shall help to elucidate the physics underlying the magnitude of this effect, and to establish structure-property relationships. Based on these relationships, suggestions for the experiment shall be made, which will allow for further testing the theoretical description. Furthermore, methods shall be developed for extracting effective spin-orbit coupling parameters from the first-principles electronic structure, which allows for a comparison with analytical models, and which may serve as a basis for a coarse-grained approach towards the simulation of building blocks for devices. In addition to the fundamentally interesting aspects of such an approach, this would allow for advancing molecular spintronics, with the potential for providing affordable and fine-tunable materials for such devices.