How to calculate spin-resolved current-coltage(i-v)characterisrics?

[guojunnan]

I'm trying to calculate the nature of spin-electron transport in chiral molecules. I first made a conjecture for the ground state using SGGA. Where the initial states are set to parallel states. Then spin-orbit coupling was introduced to calculate the spin transport properties, IV curves. Why can't I get get spin up and spin down currents respectively?

[Anders Blom]

Because spin up and down are no longer meaningful concepts in the noncollinear regime, to which spin-orbit belongs. Or put differently, s-o interaction couples the up and down spins so you no longer can have pure spin states, only spinors. You will therefore need to consider up/up and down/down currents, but also note there is up/down and down/up contributions.