Intrinsic stability of the smallest possible silver nanotube

Formation and Stability of Low-Dimensional Structures for Group VIIIB and IB Transition Metals: The Role of sd4 Hybridization

A quasi-sd⁴ hybridization state for group VIIIB and IB face-centered cubic (FCC) transition metals in low-dimensional nanostructures is identified, in contrast to the sd⁵ hybridization state in bulk. For Au, a novel three-shelled nanowire is designed with a hexagonal close-packed core in the sd⁵ hybridization, wrapped by FCC-(111) shell that adopts the quasi-sd⁴ hybridization. This new nanostructure exhibits remarkable stability and electronic properties.

First-principles simulations on suspended coinage-metal nanotubes composed of different atomic species

Substitutional doping of gold and copper atoms in a (4, 4) silver single-wall nanotube has been investigated using first-principles simulations. It is found that the Au- and Cu-substitutional doping of the tip-suspended (4, 4) Ag tube can maintain the hollow tubular structure at different alloy compositions due to the existence of a local minimum in the string tension variation with their unit cell lengths. The bonding energy differences between the mono-elements and hetero-elements and string tension may play important roles in suppressing the "self-purification" effects so that the nanoalloy tubes can be formed. Analysis of the band structure suggests that the number of conduction channels of the Ag-Au alloy tubes may lie between the pure (4, 4) Ag and Au tubes.

Coinage metal (4, 4) nanotubes, simulated by first-principles calculations

The structural stability of coinage metal nanotubes with a square cross-section has been investigated by the first-principles numerical simulations. In addition to the reported (4, 4) silver tube, it is found that the hollow (4, 4) copper and gold nanotubes can also be formed by applying an appropriate stress to an 8(A)/8(B) fcc wire. The stability of these coinage metal (4, 4) nanotubes, formed by tip-stretching the wires, has been explained by a local minimum in the string tension variation with their tube lengths. Interestingly, we have explained why a low-stress stretching is needed to obtain the (4, 4) Cu tube in contrast to a higher one for both the (4, 4) Ag and Au tubes due to the larger stiffness coefficient of copper than those of silver and gold, which could be proved by future experiments.