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

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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.