Influence of adsorbate and defect on structural and electronic properties of ultrathin silver nanotube

Using first-principles calculations based on density-functional theory, the effects of adsorbates (CO molecule, O and N atoms) and defects (an adhered atom and a monovacancy) on structural and electronic properties of the smallest (4, 4) AgNT have been systematically investigated. For CO adsorption on energetically preferred top site, the donation-backdonation process between the CO and Ag states leads to the formation of bonding/antibonding pairs, 5σb/5σa and 2πb∗/2πa∗, and the quantum conductance of AgNT decreases by 1G0 after CO adsorption. Both O and N atoms strongly interact with AgNT after adsorption, leading to a 3G0 and 2G0 of drop in quantum conductance, respectively, for the AgNT. High adsorption energy of adhesion of one Ag atom and relatively low formation energy of a monovacancy suggest that these two types of defects are likely to occur in the fabrication of AgNT. The quantum conductance of the AgNT remains unchanged for adhesion of one Ag atom, but decreases by 1G0 when a monovacancy is present.