Zigzag equilibrium structure in monatomic wires

We have applied first-principles density-functional calculations to the stu dy of the energetics, and the elastic and electronic properties of monatomi c 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 wi re is stretched, but this is not observed for K and Ca wires. In all the ca ses, the equilibrium structure is an equilateral zigzag (bond angle of 60 d egrees). Only in the case of Au, the zigzag geometry can also be stabilized for an intermediate bond angle of 131 degrees. The relationship between th e 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.