a) The modeling methods for single level system have their own limitation in practice. It is important to use the map in figure above as the guidance for the applicability of Eq 2 and Eq 3. b) Numerical integration Landauer formula (Eq 1) should provide more reasonable results relative to Eq 2 and 3. We would like to recommend it as a more general method than Eq 2 and Eq 3 for the modeling study of molecular junction study. We have included the MATLAB code for the practical use of the method in the supporting information. It is important to notice as well the limitation of the numerical integration of Eq 1. The single level is whatsoever a simplified model and it may fail to work for systems with multi transmission channel and complex transmission spectrum. On the other hand, Eq 1 neither took into consideration the effect of variation in the density of state with respect to the energy 𝐸 , and it also neglected the effect of electrostatic field under bias, like the energy level polarization, which is the basis of current rectification, and stark effect, which can make coupling strength bias dependent . Therefore, care must be taken as well when applying method 1. 𝐸 dependent DOS and bias dependent coupling could be further incorporated into the modelling method as done by Liu and Neaton.