Ab initio study of helical silver single-wall nanotubes and nanowires.pdf

Ab initio study of helical silver single-wall nanotubes and nanowires S. L. Elizondo and J. W. Mintmire Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078, USA
Received 1 September 2005; revised manuscript received 12 December 2005; published 26 January 2006 We report results for the electronic structures of extended silver single-wall nanotubes
AgSWNTs within a first-principles, all-electron self-consistent local density functional approach adapted for helical symmetry. We carried out calculations on twenty-one different AgSWNTs ranging in radii from approximately 1.3 ? to 3.6 ?. AgSWNTs with radii greater than 2.2 ? were also calculated with a silver atomic chain inserted along the nanotube axis; we refer to these composite structures as silver nanowires
AgNWs. Energetic trends for the AgSWNTs are not as predictable as expected. For example, the total energy does not necessarily decrease monotonically as nanotube radius increases, as is the case for single-wall carbon nanotubes. The conductivity of these AgSWNTs and AgNWs is also addressed. Similar to the case for helical gold nanowires, the number of conduction channels in the AgSWNTs does not always correspond to the number of atom rows comprising the nanotube. However, for all AgNWs considered, the additional silver atomic chain placed along the tube’s axis results in one additional conduction channel. DOI: 10.1103/PhysRevB.73.045431 PACS number
s: 73.22.
f, 31.10.z, 31.15.Ew, 68.65.La I. INTRODUCTION As the miniaturization of electronic devices continues to advance, nanotubes and nanowires will become increasingly important in the development of these devices. A variety of procedures have been reported for constructing both gold and silver wires with nanoscale diameters.1–10 Only one method has successfully produced gold nanowires exhibiting helical periodicity.2,3 This unique fabrication method re- ported by Takayanagi and co-workers, for constructing gold nanowires with diam