Atomic geometry, electronic structure and image state for the Si(1 1 1)–In(4×1) nanowire

We have performed a detailed theoretical study of the atomic geometry, electronic structure, and dispersion of the most tightly bound (n=1) image state for the Si(1 1 1)–In(4×1) nanowire system. The calculations were performed using ab initio pseudopotentials, based on the local density approximation and a first-order energy correction for its asymptotic classical-image behaviour. The calculated atomic geometry, within the structural model proposed by Bunk et al. [Phys. Rev. B 59 (1999) 12228], agrees well with their X-ray diffraction studies, and the electronic band structure calculations confirm the quasi-one-dimensional semimetallic behaviour, in agreement with previous photoemission studies. The anisotropic dispersion of the image state measured in a recent inverse photoemission study by Hill and McLean [Phys. Rev. Lett. 82 (1999) 2155] is verified, and an explanation based on the calculated surface corrugation potential is presented.