Structural and electronic properties of the adsorbed and defected Cu nanowires: A density-functional theory study

摘要

Using first-principles calculations based on density-functional theory, we systematically investigate the influence of adsorbates (CO molecule and O atom) and defects (adsorb one extra Cu atom and monovacancy) on the structural and electronic properties of Cu_(5-1)NW and Cu_(6-1)NW. For both nanowires, CO molecule prefers to adsorb on the top site, while O atom prefers to adsorb on the center site. The hybridization between the CO and Cu states is dominated by the donation-backdonation process, which leads to the formation of bonding/antibonding pairs, 5σ_b/5σ_a and 2π_b~*/2π_a~*. The larger adsorption energies， larger charge transfers to O adatom and larger decrease in quantum conductance 3G_0 for an O atom adsorbed on the Cu_5-1NW and Cu_(6-1)NW show both Cu_(5-1)NW and Cu_(6-1)NW can be used as an O sensor. Furthermore, the decrease in quantum conductance 1G_0 for a CO molecule adsorbed on the Cu_(6-1)NW also shows the Cu_(6-1)NW can be used to detect CO molecule. So we expect these results may have implications for CuNW based chemical sensing. High adsorption energy of one extra Cu atom and relatively low formation energy of a monovacancy suggest that these two types of defects are likely to occur in the fabrication of CuNWs. One extra Cu atom does not decrease the quantum conductance, while a Cu monovacancy leads to a drop of the quantum conductance.