Periodic boundary conditions were applied in all directions, but a vacuum gap of 30 Å was added in z-direction (transport direction). Thereby, pseudo semi-periodic conditions were enabled, where the gold surfaces were expanded along x and y direction (along the gold surfaces) but not along the transport direction due to the vacuum gap. As the transmission at the Fermi energy T (E F ) is proportional to the zero-bias conductance G 0V , the conductance could be calculated by