Zigzag equilibrium structure in monatomic wires

We have applied first-principles density-functional calculations to the study of the energetics, and the elastic and electronic properties of monatomic wires of Au, Cu, K, and Ca in linear and a planar zigzag geometries. For Cu and Au wires, the zigzag distortion is favorable even when the linear wire is stretched, but this is not observed for K and Ca wires. In all the cases, the equilibrium structure is an equilateral zigzag (bond angle of 60 degrees). Only in the case of Au, the zigzag geometry can also be stabilized for an intermediate bond angle of 131 degrees. The relationship between the bond and wire lengths is qualitatively different for the metallic (Au, Cu, and K) and semiconducting (Ca) wires. (C) 2001 Elsevier Science B.V. All rights reserved.