TRANSPORT PROPERTY OF TWO ISOELECTRONIC MOLECULES

Transport properties of two isoelectronic conjugated molecules, 1, 2-bis (4'-mercaptophenyl) diazene (BMPD) and 1, 2-bis (4'-mercaptophenyl) ethene (BMPE), sandwiched between two Au (111) surfaces, are investigated by using nonequilibrium Green's function combining with density functional theory. The Fermi level lies close to the transmission peak coming from the perturbed highest occupied molecular orbital. The conductive ability of BMPD molecule is a little stronger than that of BMPE. The current–voltage (I–V) curves for both molecular junctions are almost linear at small bias voltage, but show nonlinear character in large bias case. There is a negative differential resistance behavior appeared in the I–V curve for the BMPE junction without considering the molecular atomic relaxation due to the existence of the leads.