Comment on “Spin-orbit interaction and spin selectivity for tunneling electron transfer in DNA”

The observation of chiral-induced spin selectivity (CISS) in biological molecules still awaits a full theoretical explanation. In recent Rapid Communication, Varela et al. [Phys. Rev. B 101, 241410(R) (2020)] presented model for electron transport by tunneling the presence spin-orbit interactions. They then claimed that their produces strong asymmetry due to intrinsic atomic strength. As Hamiltonian is time-reversal symmetric, this result contradicts theorem Bardarson [J. Phys. A: Math. Theor. 41, 405203 (2008)], which states such cannot generate between two terminals (in there are only spin-up and spin-down channel). Here we solve proposed show it does not yield any asymmetry, therefore explain observed CISS effect.