We report theoretical investigations oil tile role of interracial bonding mechanism and its resulting structures to quantum transport in molecular wires. Two bonding mechanisms for the Au-S bond in an Au（111） / 1,4-...We report theoretical investigations oil tile role of interracial bonding mechanism and its resulting structures to quantum transport in molecular wires. Two bonding mechanisms for the Au-S bond in an Au（111） / 1,4-benzenedithiol（BDT）/Au（111） junction were identified by ab initio calculation, con- firmed by a recent experiment, which, we showed, critically control charge conduction. It was found, for Au/BDT/Aujunctions, the hydrogen atom, bound by a dative bond to the Sulfur, is energetically non-dissociativeafter the interface formation. The calculated conductance and junction breakdown forces of H-non-dissociative Au/BDT/Au devices are consistent with the experimental values, while the H-dissociated devices, with the interface governed by typical covalent bonding, give conduc- tance more than an order of magnitude larger. By examining the scattering states that traverse the junctions, we have revealed that mechanical and electric properties of a junction have strong corre- lation with the bonding configuration. This work clearly demonstrates that the interracial details. rather than previously believed ninny-body effects, is of vital importance for correctly predicting equilibrium conductance of molecular junctions; and manifests that the interfaeial contact must be carefully understood for investigating quantum transport properties of molecular nanoelectronics.展开更多
文摘We report theoretical investigations oil tile role of interracial bonding mechanism and its resulting structures to quantum transport in molecular wires. Two bonding mechanisms for the Au-S bond in an Au（111） / 1,4-benzenedithiol（BDT）/Au（111） junction were identified by ab initio calculation, con- firmed by a recent experiment, which, we showed, critically control charge conduction. It was found, for Au/BDT/Aujunctions, the hydrogen atom, bound by a dative bond to the Sulfur, is energetically non-dissociativeafter the interface formation. The calculated conductance and junction breakdown forces of H-non-dissociative Au/BDT/Au devices are consistent with the experimental values, while the H-dissociated devices, with the interface governed by typical covalent bonding, give conduc- tance more than an order of magnitude larger. By examining the scattering states that traverse the junctions, we have revealed that mechanical and electric properties of a junction have strong corre- lation with the bonding configuration. This work clearly demonstrates that the interracial details. rather than previously believed ninny-body effects, is of vital importance for correctly predicting equilibrium conductance of molecular junctions; and manifests that the interfaeial contact must be carefully understood for investigating quantum transport properties of molecular nanoelectronics.
