Adsorbate and defect effects on electronic and transport properties of gold nanotubes

Abstract

First-principles calculations have been performed to study the effects of adsorbates (COmolecules and O atoms) and defects on electronic structures and transport properties ofAu nanotubes (Au(5, 3) and Au(5, 5)). For CO adsorption, various adsorptionsites of CO on the Au tubes were considered. The vibrational frequency of theCO molecule was found to be very different for two nearly degenerate stableadsorption configurations of Au(5, 3), implying the possibility of distinguishingthese two configurations via measuring the vibrational frequency of CO inexperiments. After CO adsorption, the conductance of Au(5, 3) decreases by0.9G0 and the conductance of Au(5, 5) decreases by approximately0.5G0. For O-adsorbed Au tubes, O atoms strongly interact with Au tubes, leading to around2G0 of drop in conductance for both Au tubes. These results may have implicationsfor Au-tube-based chemical sensing. When a monovacancy defect is present,we found that, for both tubes, the conductance decreases by around1G0. Another type of defect arising from the adhesion of one Au atom is also considered. For thiscase, it is found that, for the Au(5, 3) tube, the defect decreases the conductance by nearly1G0, whereas for Au(5, 5), the decrease in conductance is only0.3G0.