Transmission coefficients of S–Au–S junction. Panels (a) and (b) are the transmission coefficients of spin-up electrons and spin-down electrons at the distance of 3.5 Å at different biases, while panels (c) and (d) are the transmission coefficients of spin-up electrons and spin-down electrons at different distances at bias of 0.3 V. Fermi energy of S–Au–S junction is stable in about −6.40 eV at various distances.