Theoretical investigation of metal-molecule interface with terminal group

We studied the metal/molecule interface linkage effects through metal-molecule-metal systems by first principles method, which is based on the density functional theory (DFT) with norm conserving nonlocal pseudopotentials and nonequilibrium Green´s functions (NEGF´s) to calculate the charge distribution for open metal-molecule-metal systems. Metal electrodes were described through 3-D atomic model instead of a non-atomic (like jellium model) description of the electrodes. Several open systems were constructed, optimized and simulated. Sulphur atom (S) and cyano-group (CN) were employed to connect electrodes Au and molecule borazine. The current-voltage (I-V) characteristics, density of states (DOS), and the transmission function (TF) of constructed systems were investigated. Results show that transmission properties of the systems are affected a lot by the terminal group. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are shifted and the magnitudes of TF are changed. Simulated I-V characteristics show that the system with terminal group CN presents better conductance.