Structural and electronic properties of Au, Pt, and their bimetallic nanowires

We have carried out first-principles, full-potential, density-functional calculations on different types (linear, zig-zag, double zig-zag, and tetragonal) of infinite, periodic, atomic wires of Au and Pt as well as on mixed chains containing both Au and Pt. In particular, structural degrees of freedom are optimized, and the band structures of the different types of wires are reported and discussed. The bond lengths for Au and Pt are found to be somewhere between those of the corresponding dimer and those of the corresponding crystalline phases of Au and Pt. The bond length for all three systems is progressively increased as we move from the linear to the tetragonal structure, as the number of nearest-neighbor atoms is increased. Moreover, the bond angles are around 60°as in crystalline system. The bond length for Au-Pt wire is in between the values of pure Au and Pt wires and the bond angles around 60°suggesting the possible formation of Au-Pt bimetallic materials. All wires are found to be metallic and the bands closest to the Fermi level, responsible for conduction, are analyzed and discussed.