A linear dependence of the logarithmic zero-bias conductance on the alkane chain length can be observed in Figure , which is consistent with Equation (1). The Fermi transmissions of dithiolates and monothiolates of the same chain length are comparable, and a slope of -1.4/CH 2 was obtained from the linear fit in both cases. From the slope and the increase of the intersurface distance δ per carbon unit, obtained from our MD simulations, the tunneling decay constant β can be calculated. Thereby, a tunneling decay constant of 1.2 Å -1 and 1.3 Å -1 was obtained for dithiolates and monothiolates, respectively. The value for monothiolates is in good agreement with experimentally obtained decay constants of Wuelfing et al. on alkanethiolate-monolayer-protected 2.2 nm-diameter gold clusters. They calculated a decay constant of 1.2/CH 2 unit, equivalent to 0.8 Å -1 . Lindsay and co-workers determined a decay constant for alkanedithiols in single-molecule junctions of 0.57 Å -1 , which is significantly lower than our calculated β. However, their experimentally obtained value also deviated from their estimation based on first-principles electronic structure calculations on alkanedithiol cross-linked Au(111) SAMs. These theoretical calculations suggested a decay constant of 1 per carbon unit. In another experimental study, Schlicke et al. investigated the conductivity dependence on the chain length of alkanedithiols. From their data, a tunneling decay constant of around 1.1 Å -1 was obtained, which is in good agreement with our decay constant.