Ab initio study of structural, electronic and dielectric properties of free standing ultrathin nanowires of noble metals

Structural, electronic and dielectric properties of free standing ultrathin nanowires of noble metals (Cu, Ag, Au and Pt) in linear, dimer, ladder and zigzag topologies have been studied by using ab initio density functional theory. Among the studied topologies of all the noble metals, ladder topology has been found most stable while the dimer topology was least stable. The ballistic conductance of all the studied wires except Pt wires, has been found to be topology dependent. The dielectric properties of the studied nanowires have been found to be significantly different from their bulk counterparts. A prominent peak structure in imaginary part of dielectric function (ϵ2)(ϵ2), which reveals interband transitions in electronic band structure, has been found between 0.5 and 2.0 eV for linear, dimer topologies of Cu and Au wires along with all the topologies of Pt wires. The reflectance edge of different topologies of all the nanowires except ladder topology of Pt, has been found in infrared region, therefore, shows perfect reflectivity in the infrared region and makes them non-absorbing transparent conductors to the visible region. The ultrathin transparent conductors may find many useful applications in the optoelectronic devices.

Graphical abstractWe present electronic and dielectric response of Cu, Ag, Au and Pt nanowires in four topologies namely linear, dimer, ladder and zigzag. Illustration 1: electronic band structure and corresponding total and partial DOS for (a) linear, (b) dimer, (c) ladder and (d) zigzag topology of Pt nanowires. The number of bands crossing the fermi energy is 3 in each topology. The Fermi energy has been set at 0 eV. The possible interband transitions responsible for the structure peaks in ϵ2ϵ2 of Pt wires have also been shown.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The binding energy of Pt nanowires was largest whereas Ag nanowire having smallest. ► Ballistic conductance increases for ladder and zigzag topology of Cu, Ag and Au. ► Ballistic conductance remains same for all the topologies of Pt wire. ► Dielectric properties of nanowires change significantly with the topology. ► Reflectance edge for the studied topologies of nanowires is found in infrared region.