Coherent spin transport in a natural helical protein molecule

Highlights: • Spin transport calculation based on Landauer–Büttiker formula. • NEGF-DFT in the presence of spin–orbit coupling. • Spin polarization in a helical protein molecule. Coherent spin transport in a protein molecule connected to the gold electrodes was calculated using the Landauer–Büttiker formula with NEGF-DFT. A natural helical peptide and a non-helical oligoglycine were used as the model protein molecules. The NEGF-DFT calculations were performed in the presence of spin–orbit coupling. The helical peptide provided a certain spin polarization; however, oligoglycine suppressed the spin polarization. It was found that an amide group located on a specific region overlapping with the frontier orbital exhibited a relatively high spin polarization. It further suggested that the helical peptide structure derived from the closely-packed protein structure was related to spin polarization in the presence of spin–orbit coupling.