Ab initiostudy of helical silver single-wall nanotubes and nanowires

Abstract

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 $1.3\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ to $3.6\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$. AgSWNTs with radii greater than $2.2\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ 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.