Abstarct: Due to the high power consumption and expensive fabrication procedure approaches of Nanoscale silicon device, molecules, that are small in size and have adjustable feature, were replaced as the main component in electronic devices. One of the significant points that catch researchers eyes is single molecule diode (molecular diode) is molecule have the responsibility of transferring electrons from an electrode to another one. In this research, single molecule diode (molecular diode) is simulated with the method of density function theory (DFT) and self-consistent field (SCF) in order to calculate the coupling and check the conductivity. In this simulation, at first according to DFT method and using Gaussian software the device is simulated, then molecule states and energies at 0V were obtained. Next step is to calculate the electrode-molecule coupling using electrode and molecule Hamiltonian obtained by Huckel parameters and site to state conversion and Fermi-Golden rule. The result shows that the molecule coupling is dependent on electrode and molecule type (electrode geometry and electrode to molecule distance). Gold-B80, Gold-C60, Silver-B80, Silver-C60 coupling, with a one dimensional electrode and 50 atoms and the distance of 5 angstrom is 105, 29, 26, 6 (meV) respectively. Also for Gold-B80 coupling with increasing number of gold atoms from 1 to 100, the coupling increased from 50 to 105 (meV). Geometrical structure is impressive in coupling as gold electrode coupling is higher than silver. Electrode-device coupling is dependent on distance, were by increasing distance from 5 to 5.5 angstrom, the coupling will be decreased from 0.04 to 0.002 (eV). After calculating Electrode-molecule coupling, where is the most significant parameter in electron transferring, this can be used in obtaining Current-Voltage curves and conductivity of device. Simulations express that external applied field can cause in increase or decrease of coupling, and due to that cause an increase or decrease in current and conductivity depends on molecule type.