The Influence of Electronic Structure Modelling and Junction Structure on First-Principles Chiral Induced Spin Selectivity

We have carried out a comprehensive study of the influence of electronic structure modeling and junction structure description on the first-principles calculation of the spin polarization in molecular junctions caused by the chiral induced spin selectivity (CISS) effect. We explore the limits and the sensitivity to modelling decisions of a Landauer / Green’s function / density functional theory approach to CISS. We find that although the CISS effect is entirely attributed in the literature to molecular spin filtering, spin-orbit coupling being partially inherited from the metal electrodes plays an important role in our calculations, even though this effect cannot explain the experi- mental conductance results. Also, an important dependence on the specific description of exchange interaction and spin–orbit coupling is manifest in our approach. This is important because the interplay between exchange effects and spin-orbit coupling may play an important role in the description of the junction magnetic response. Our calculations are relevant for the whole field of spin-polarized electron transport and electron transfer because there is still an open discussion in the literature about the detailed underlying mechanism and the magnitude of relevant physical parameters that need to be included to achieve a consistent description of the CISS effect